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banterly.net_ghost4.rss.xml - sfeed_tests - sfeed tests and RSS and Atom files |
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banterly.net_ghost4.rss.xml (179684B) |
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1 <?xml version="1.0" encoding="UTF-8"?><rss xmlns:dc="http://purl.org/dc/… |
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2 ]]></description><link>https://www.banterly.net/2021/07/31/new-in-git-sw… |
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3 <img src="https://www.banterly.net/content/images/2021/07/1200px-Git-log… |
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4 </blockquote> |
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5 <p>For those that work with git for some time, it is not often that you … |
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6 <ul> |
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7 <li><code>git restore</code></li> |
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8 <li><code>git switch</code></li> |
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9 </ul> |
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10 <p>To understand why they came to be, let's first visit our old fri… |
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11 <!--kg-card-end: markdown--><figure class="kg-card kg-image-card"><img s… |
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12 <p><code>git checkout</code> is one of the many reasons why newcomers fi… |
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13 The way most people use it is to switch the active branch in their local… |
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14 <p><code>git checkout develop</code></p> |
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15 <p>You can also make your HEAD pointer reference a specific commit inste… |
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16 <p><code>git checkout f8c540805b7e16753c65619ca3d7514178353f39</code></p> |
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17 <p>Where things get tricky is that if you provide a file as an argument … |
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18 For example, if you checked out the develop branch and you made some cha… |
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19 <p><code>git checkout -- test.txt</code></p> |
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20 <h3 id="amethodtothemadness">A method to the madness</h3> |
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21 <p>If you first look at these two behaviors you might think that it does… |
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22 <p><code>git checkout <tree-ish> -- <pathspec></code></p> |
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23 <p>What is <code><tree-ish></code> ? It can mean a lot of differen… |
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24 <p><code>git checkout main -- test.txt</code></p> |
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25 <p>With this in mind, maybe things start to make sense. When you provide… |
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26 <!--kg-card-end: markdown--><figure class="kg-card kg-image-card"><img s… |
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27 <p>So even if things may start to make sense after reading the previous … |
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28 <h3 id="switch">Switch</h3> |
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29 <p>This one implements the behavior of git checkout when running it only… |
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30 <p><code>git switch develop</code></p> |
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31 <p>While with <code>git checkout</code> you can switch to a commit and t… |
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32 <p><code>git switch -d f8c540805b7e16753c65619ca3d7514178353f39</code></… |
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33 <p>Another difference is that with git checkout you can create and switc… |
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34 <code>git checkout -b new_branch</code></p> |
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35 <p>You can do the same with the new one, but the flag is -c:<br> |
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36 <code>git switch -c new_branch</code></p> |
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37 <h3 id="restore">Restore</h3> |
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38 <p>This one implements the behavior of git when running it against a fil… |
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39 <p><code>git restore -- test.txt</code></p> |
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40 <!--kg-card-end: markdown--><!--kg-card-begin: markdown--><h1 id="conclu… |
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41 <p>These methods are still marked experimental, but for all intents and … |
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42 <p>More details about the two commands can be found in their git documen… |
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43 <ul> |
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44 <li><a href="https://git-scm.com/docs/git-switch">git switch</a></li> |
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45 <li><a href="https://git-scm.com/docs/git-restore">git restore</a></li> |
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46 </ul> |
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47 <!--kg-card-end: markdown-->]]></content:encoded></item><item><title><![… |
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48 <p>Due to work and family obligations, this took more time than expected… |
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49 <p>I will follow up this article with part 2 where I will explain more t… |
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50 <h2 id="solvingaproblem">Solving a problem</h2> |
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51 <p>Firstly, if you are planning on writing a plugin(or any piece of soft… |
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52 <h3 id="builders">Builders</h3> |
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53 <p>If you are coming from the Java or C# world(and not only) I assume yo… |
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54 <p>It always irked me the wrong way that, while being a lot better than … |
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55 <h3 id="solutions">Solutions</h3> |
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56 <p>My first attempt at solving this problem was to define a series of Bu… |
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57 <p>In practice, it turns out that the Step Builder pattern is not ideal … |
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58 <p>The previously mentioned post actually was the inspiration for my fin… |
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59 <!--kg-card-end: markdown--><figure class="kg-card kg-image-card kg-card… |
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60 <p>Now let us get started with some Intellij platform quirks that you sh… |
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61 <h3 id="1extensionpointshelp">1. Extension Points Help</h3> |
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62 <p>Extension Points are quite a central concept in Intellij plugin devel… |
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63 I discovered it quite late, but luckily there is a tool that JetBrains h… |
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64 You can access it <a href="https://plugins.jetbrains.com/intellij-platfo… |
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65 <ol> |
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66 <li>get from <a href="https://plugins.jetbrains.com/docs/intellij/extens… |
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67 <li>search for the one that you think will probably help you to accompli… |
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68 <li>look at the related platform class which may have some documentation… |
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69 <li>look for other plugins implementing it since that will most likely a… |
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70 </ol> |
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71 <h3 id="2enablejavafunctionality">2. Enable Java functionality</h3> |
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72 <p>My plugin is in Java developed for Java. I had a lot of headaches whe… |
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73 <ul> |
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74 <li>declare in your plugin.xml file the following:</li> |
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75 </ul> |
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76 <pre><code class="language-xml"><depends>com.intellij.modules.java… |
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77 </code></pre> |
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78 <ul> |
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79 <li>if you are using the gradle-intellij-plugin(as you should) then you … |
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80 </ul> |
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81 <pre><code class="language-groovy">intellij { |
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82 plugins = ['com.intellij.java'] |
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83 // ... |
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84 } |
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85 </code></pre> |
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86 <p>The above is for groovy based graddle. For kotlin based graddle use:<… |
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87 <pre><code class="language-kotlin">intellij { |
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88 setPlugins("java") |
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89 // ... |
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90 } |
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91 </code></pre> |
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92 <h3 id="psiviewer">PsiViewer</h3> |
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93 <p>In the Intellij platform, the contents of a file are structured under… |
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94 A very helpful tool that will allow you to experiment and discover how t… |
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95 <!--kg-card-end: markdown--><figure class="kg-card kg-image-card"><img s… |
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96 <pre><code>idea.is.internal=true |
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97 </code></pre> |
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98 <h3 id="debugging">Debugging</h3> |
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99 <p>For sure you will want to debug your plugin in order to solve some is… |
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100 First, you should be happy to know that you do not need to create any sp… |
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101 <p>If you try to do this as-is, you will probably encounter quite fast w… |
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102 <ul> |
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103 <li><em>-Didea.auto.reload.plugins=false</em></li> |
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104 <li><em>-Didea.ProcessCanceledException=disabled</em></li> |
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105 </ul> |
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106 <p>The way I managed to do this was with the following configuration in … |
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107 <pre><code class="language-kotlin"> withType<org.jetbrains.intellij.t… |
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108 jvmArgs("-Didea.auto.reload.plugins=false") |
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109 jvmArgs("-Didea.ProcessCanceledException=disabled") |
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110 } |
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111 </code></pre> |
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112 <h2 id="tobecontinued">To be continued</h2> |
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113 <p>This was a fun experience for me and will try to improve on the curre… |
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114 <!--kg-card-end: markdown-->]]></content:encoded></item><item><title><![… |
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115 <img src="https://www.banterly.net/content/images/2020/04/The-Silver-Lin… |
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116 </blockquote> |
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117 <p>As you all know, maybe too much which is partly the point of this pos… |
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118 <h2 id="doomsayersclub">Doomsayers Club</h2> |
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119 <p>Monitoring the online sphere during the last few weeks, I observed so… |
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120 <!--kg-card-end: markdown--><figure class="kg-card kg-image-card"><img s… |
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121 <p>I want to put in the same category the journalists who either do not … |
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122 <p>Everyday I see a titles that are either misleading or are meant to in… |
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123 <p>I will give two example of titles that I see almost every day.</p> |
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124 <ul> |
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125 <li>"The number of new cases has skyrocketed" - this I saw a l… |
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126 <li>"Scary new number of deaths today: 1000". Regarding this o… |
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127 <ul> |
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128 <li>At the time of this writing there have been reported 65 000 deaths w… |
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129 <li>In the first 10 hours of this day it is estimated that 65 000 deaths… |
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130 <li>Since the beginning of the year it is estimated around 15 000 000 pe… |
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131 </ul> |
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132 </li> |
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133 </ul> |
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134 <p>Looking at the examples above I hope you understand why the scary and… |
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135 <!--kg-card-end: markdown--><figure class="kg-card kg-image-card"><img s… |
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136 <h2 id="puttingsomepositivelightintoallthismess">Putting some positive l… |
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137 <p>Today I want to do the opposite of what I mentioned above. I will com… |
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138 <p>Before I begin I want to be clear, I am not dismissing all the negati… |
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139 <!--kg-card-end: markdown--><figure class="kg-card kg-image-card"><img s… |
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140 <p>"Wash your hands thoroughly when coming from outside!", &qu… |
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141 <!--kg-card-end: markdown--><!--kg-card-begin: markdown--><h3 id="prepar… |
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142 <p>COVID-19 has shown that the world is not prepared for an epidemic of … |
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143 <!--kg-card-end: markdown--><!--kg-card-begin: markdown--><h3 id="antiva… |
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144 <p>Most anti-vaxxers, at least the moderate ones, consider vaccines too … |
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145 Now with the whole world witnessing how much global health and economic … |
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146 <!--kg-card-end: markdown--><figure class="kg-card kg-image-card"><img s… |
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147 <p>The current situation has forced organizations to widen the range of … |
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148 <ul> |
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149 <li>The employee saves on commute time, time which he can spend on learn… |
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150 <li>For employers, it would allow them to transform their local pool of … |
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151 <li>As an extra benefit, less commuters will mean less traffic which mea… |
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152 </ul> |
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153 <p>Of course this is not possible for everyone and some may just prefer … |
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154 <!--kg-card-end: markdown--><!--kg-card-begin: markdown--><h3 id="animal… |
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155 <p>With people suffering from loneliness during these times of isolation… |
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156 <!--kg-card-end: markdown--><figure class="kg-card kg-image-card"><img s… |
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157 <p>There are a lot of jobs that cannot be performed from home. As a resu… |
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158 The idea is that if we as a society can survive and even prosper without… |
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159 <!--kg-card-end: markdown--><!--kg-card-begin: markdown--><h3 id="lessfo… |
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160 <p>Another thing that has been exposed during this pandemic is the amoun… |
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161 <!--kg-card-end: markdown--><!--kg-card-begin: markdown--><h3 id="lessdi… |
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162 <p>Polarization has been skyrocketing in the last decade so one of the h… |
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163 <!--kg-card-end: markdown--><!--kg-card-begin: markdown--><h2 id></h2> |
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164 <!--kg-card-end: markdown--><!--kg-card-begin: markdown--><h2 id="sharey… |
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165 <p>Those are some of the main positive ideas I identified. If you make a… |
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166 <!--kg-card-end: markdown--><figure class="kg-card kg-image-card"><img s… |
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167 <img src="https://www.banterly.net/content/images/2020/02/meme2.jpg" alt… |
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168 </blockquote> |
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169 <p>Sadly for me (I guess happily for my sanity) sometimes when I read an… |
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170 <p>For some crazy reason, recently I revisited the two well known graph … |
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171 <!--kg-card-end: markdown--><figure class="kg-card kg-image-card"><img s… |
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172 <!--kg-card-end: markdown--><figure class="kg-card kg-image-card"><img s… |
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173 <p>BFS starts with a node of the graph which will act as a root node in … |
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174 For the example above the traversal order would be:</p> |
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175 <ul> |
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176 <li>Level 0: 1</li> |
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177 <li>Level 1: 2 -> 3 -> 4</li> |
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178 <li>Level 2: 5 -> 6 -> 7</li> |
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179 <li>Level 3: 8 -> 9</li> |
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180 </ul> |
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181 <p>The classic implementation of this algorithm is iterative and involve… |
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182 <pre><code class="language-java">void breadthFirstTraversal(Node root) { |
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183 if (root == null) |
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184 return; |
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185 |
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186 //Create and initialize the set which |
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187 //will contain discovered nodes |
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188 Set<Node> discovered = new HashSet<>(); |
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189 discovered.add(root); |
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190 |
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191 //Create and initialize queue which |
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192 //will contain the nodes left to visit |
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193 Deque<Node> queue = new ArrayDeque<>(); |
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194 queue.offer(root); |
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195 |
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196 while (!queue.isEmpty()) { |
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197 Node current = queue.poll(); |
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198 |
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199 //visit the node; in this case just print |
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200 // the node value |
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201 System.out.println(current.getValue()); |
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202 |
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203 for (Node child : current.getChildren()) { |
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204 //add to the queue any child node of the |
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205 //current node that has not already been discovered |
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206 //and also add it to the set of |
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207 //discovered nodes |
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208 if (!discovered.contains(child)) { |
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209 queue.offer(child); |
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210 discovered.add(child); |
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211 } |
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212 } |
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213 } |
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214 } |
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215 </code></pre> |
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216 <!--kg-card-end: markdown--><!--kg-card-begin: markdown--><h2 id="depthf… |
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217 <p>Now that we know what BFS is, it should be intuitive how using a DFS … |
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218 <ul> |
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219 <li>Branch 1: 1 -> 2 -> 5 -> 8 -> 7 > 9</li> |
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220 <li>Branch 2: 6</li> |
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221 <li>Branch 3: 3 -> 4</li> |
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222 </ul> |
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223 <!--kg-card-end: markdown--><figure class="kg-card kg-image-card"><img s… |
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224 <pre><code class="language-java">void depthFirstTraversal(Node root){ |
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225 if(root == null){ |
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226 return; |
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227 } |
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228 |
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229 //initialize the set which will contain |
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230 // our discovered nodes |
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231 Set<Node> discovered = new HashSet<>(); |
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232 //call the recursive function starting |
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233 //with the provided root |
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234 dfsRecursive(root, discovered); |
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235 } |
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236 |
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237 void dfsRecursive(Node current, Set<Node> discovered){ |
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238 //mark the node as discovered |
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239 discovered.add(current); |
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240 |
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241 //visit the node; in this case we just |
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242 //print the value of the node |
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243 System.out.println(current.getValue()); |
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244 |
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245 //recursively call the function on all of |
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246 //the children of the current node if |
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247 //they have not already been discovered |
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248 for(Node child : current.getChildren()){ |
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249 if(!discovered.contains(child)) { |
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250 dfsRecursive(child, discovered); |
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251 } |
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252 } |
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253 } |
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254 </code></pre> |
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255 <p>At this point your teacher will say: "You know what? To help you… |
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256 1. Use a stack instead of a queue.<br> |
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257 2. Check if we have visited a node after we pop from the stack. This is … |
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258 <p>The classic implementation looks something like this (even on Wikiped… |
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259 <pre><code class="language-java">void depthFirstTraversalIterative(Node … |
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260 if (root == null) |
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261 return; |
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262 |
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263 //Create the set which |
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264 // will contain discovered nodes |
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265 Set<Node> discovered = new HashSet<>(); |
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266 |
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267 //Create and initialize stack which |
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268 // will contain the nodes left to visit |
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269 Deque<Node> stack = new ArrayDeque<>(); |
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270 stack.push(root); |
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271 |
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272 while (!stack.isEmpty()) { |
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273 Node current = stack.pop(); |
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274 |
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275 if(!discovered.contains(current)){ |
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276 discovered.add(current); |
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277 |
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278 //visit the node; in this case just print |
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279 // the node value |
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280 System.out.println(current.getValue()); |
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281 |
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282 //add to the stack all the children |
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283 //of the current node |
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284 for(Node child : current.getChildren()){ |
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285 stack.push(child); |
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286 } |
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287 } |
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288 } |
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289 } |
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290 </code></pre> |
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291 <p>The student runs the two versions of DFS and he sees that the results… |
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292 <!--kg-card-end: markdown--><figure class="kg-card kg-image-card"><img s… |
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293 <p>A more inquisitive mind will stop and ask: Wait a minute, where do th… |
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294 <p>The first one is usually answered with the following: When implementi… |
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295 <p>The second difference is not usually discussed though and here things… |
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296 First let's ask ourselves why in the BFS implementation we check if… |
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297 To answer that let's see what happens if we check after we poll the… |
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298 Node 4 will in both cases be already in our queue. If we do what we usua… |
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299 <!--kg-card-end: markdown--><figure class="kg-card kg-image-card"><img s… |
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300 <!--kg-card-end: markdown--><figure class="kg-card kg-image-card"><img s… |
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301 <p>If we turn our attention to the DFS iterative version we can think th… |
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302 <!--kg-card-end: markdown--><figure class="kg-card kg-image-card"><img s… |
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303 <li>Branch 1: 1 -> 2 -> 5 -> 8</li> |
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304 <li>Branch 2: 6</li> |
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305 <li>Branch 3: 7 -> 9</li> |
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306 <li>Branch 4: 3</li> |
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307 <li>Branch 5: 4</li> |
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308 </ul> |
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309 <p>Wait what? We get different result than in the recursive approach...t… |
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310 <!--kg-card-end: markdown--><!--kg-card-begin: markdown--><h2 id="beingm… |
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311 <p>So what is happening here? We need to realize that just by using a st… |
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312 <p>If you think a little more in depth about what the recursive version … |
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313 <p>In our iterative approach we save all the children on the stack with … |
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314 <p>So I think here is where people are misled because when we take all i… |
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315 <ul> |
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316 <li>When we implement BFS we are being taught that we do not want duplic… |
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317 <li>When we implement iterative DFS we are being taught to forget about … |
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318 </ul> |
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319 <p>The second teaching seems contradictory with the first one. If this i… |
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320 <p>Because of the differences between the inner workings of the recursiv… |
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321 <!--kg-card-end: markdown--><figure class="kg-card kg-image-card"><img s… |
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322 <!--kg-card-end: markdown--><!--kg-card-begin: markdown--><h2 id="truedf… |
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323 <p>The good news is that once we actually understand what the recursive … |
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324 <pre><code class="language-java">// data structure for storing the requi… |
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325 class TraversalInfo{ |
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326 Node parent; |
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327 int childPos; |
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328 |
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329 public TraversalInfo(Node parent, int childPos) { |
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330 this.parent = parent; |
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331 this.childPos = childPos; |
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332 } |
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333 |
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334 public Node getParent() { |
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335 return parent; |
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336 } |
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337 |
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338 |
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339 public int getChildPos() { |
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340 return childPos; |
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341 } |
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342 |
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343 public void setChildPos(int childPos) { |
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344 this.childPos = childPos; |
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345 } |
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346 } |
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347 |
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348 void trueDepthFirstTraversalIterative(Node root){ |
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349 |
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350 //as always create and initialize |
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351 //the set of discovered nodes |
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352 Set<Node> discovered = new HashSet<>(); |
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353 discovered.add(root); |
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354 |
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355 //create and initialize the stack which will |
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356 //indicate which node to visit next. You can |
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357 //observer that we are not saving anymore directly |
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358 //what node to visit next, but a parent node and |
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359 //the index of its child that we should visit next |
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360 Deque<TraversalInfo> stack = new ArrayDeque<>(); |
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361 stack.push(new TraversalInfo(root, 0)); |
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362 |
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363 //we visit the root node before going |
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364 //into our loop |
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365 System.out.println(root.getValue()); |
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366 |
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367 |
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368 while (!stack.isEmpty()) { |
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369 TraversalInfo current = stack.pop(); |
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370 Node currentParent = current.getParent(); |
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371 int currentChildPos = current.getChildPos(); |
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372 |
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373 //we check if there are more child nodes |
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374 if(currentChildPos < currentParent.getChildren().size()){ |
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375 Node child = currentParent.getChildren().get(currentChil… |
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376 //we save in the stack the next child index |
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377 //together with its parent |
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378 current.setChildPos(currentChildPos + 1); |
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379 stack.push(current); |
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380 |
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381 //check if current child discovered already |
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382 if(!discovered.contains(child)){ |
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383 //add it to the set of discovered nodes |
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384 discovered.add(child); |
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385 //visit the child; in this case just print out its v… |
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386 System.out.println(child); |
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387 //add to the stack the info for visiting its child n… |
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388 //starting from the first one |
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389 stack.push(new TraversalInfo(child, 0)); |
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390 } |
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391 } |
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392 } |
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393 } |
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394 |
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395 </code></pre> |
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396 <p>As we can see this implementation is a little more complex than the o… |
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397 <p>In some circles this iterative implementation and the recursive one a… |
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398 <!--kg-card-end: markdown--><figure class="kg-card kg-image-card"><img s… |
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399 <p>Let me know in the comments for how many of you this was obvious from… |
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400 <p>Also let me know of any other simmilar example that you may have.</p> |
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401 <p>If you like the content do not forget to subscribe!</p> |
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402 <!--kg-card-end: markdown-->]]></content:encoded></item><item><title><![… |
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403 For a while know, I became more and more amazed on how useful enums are … |
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404 <!--kg-card-end: markdown--><figure class="kg-card kg-image-card"><img s… |
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405 <!--kg-card-end: markdown--><!--kg-card-begin: markdown--><h2 id="whatis… |
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406 <p>In Java enum is short for Enumerated type and in other parts it is al… |
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407 <p>They are data types that consist of a set of named values called eith… |
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408 <p>Basically they define a type of which only certain values are possibl… |
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409 <p>Specific to Java, an enum has quite an extended behavior: it is like … |
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410 <p>If this sounds too abstract, let us give an example that will introdu… |
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411 <!--kg-card-end: markdown--><figure class="kg-card kg-image-card"><img s… |
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412 <p>Let's imagine that we have a function that accepts as a paramete… |
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413 <pre><code class="language-java">public void function(String dayOfWeek){ |
|
414 //do stuff |
|
415 } |
|
416 </code></pre> |
|
417 <p>And a user would call it like this:</p> |
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418 <pre><code class="language-java">// some logic |
|
419 function("Thursday"); |
|
420 // some other logic |
|
421 </code></pre> |
|
422 <p>One big problem with this is that a user could pass anything to our f… |
|
423 <pre><code class="language-java">// some logic |
|
424 function("banterly"); |
|
425 // some other logic |
|
426 </code></pre> |
|
427 <p>A user could either be making a typo, pass in a wrong value or just d… |
|
428 <p>Another serious implication is performance degradation: if the functi… |
|
429 <!--kg-card-end: markdown--><figure class="kg-card kg-image-card"><img s… |
|
430 <pre><code class="language-java">public static final int MONDAY = 1; |
|
431 public static final int TUESDAY = 2; |
|
432 public static final int WEDNESDAY = 3; |
|
433 public static final int THURSDAY = 4; |
|
434 public static final int FRIDAY = 5; |
|
435 public static final int SATURDAY = 6; |
|
436 public static final int SUNDAY = 7; |
|
437 |
|
438 public void function(int weekOfDay){ |
|
439 //do stuff |
|
440 } |
|
441 |
|
442 //call it later like this |
|
443 function(SUNDAY); |
|
444 |
|
445 </code></pre> |
|
446 <p>This solves the performance problem and it allows the users to pass i… |
|
447 <pre><code class="language-java">//traffic lights |
|
448 public static final int GREEN = 0; |
|
449 public static final int ORANGE = 1; |
|
450 public static final int RED = 2; |
|
451 |
|
452 //for fruits |
|
453 public static final int PEAR = 0; |
|
454 public static final int ORANGE = 1; // will give a compile error since O… |
|
455 public static final int APPLE = 2; |
|
456 </code></pre> |
|
457 <p>If defined in the same class the above will not compile, so you will … |
|
458 <pre><code class="language-java">public static final int TRAFFIC_LIGHT_O… |
|
459 public static final int FRUIT_ORANGE = 1; |
|
460 </code></pre> |
|
461 <p>Another issue with these definitions is that a function can now accep… |
|
462 <p>I hope this entire essay convinced you why it is not a good idea to u… |
|
463 <h3 id="usingenumsempoweringtheuserandthecompiler">Using enums - Empower… |
|
464 <p>Let us define a very simple enum that will represent the days of the … |
|
465 <pre><code class="language-java">enum Weekday {MONDAY, TUESDAY, WEDNESDA… |
|
466 </code></pre> |
|
467 <p>Now we can define our function to take a parameter of type Weekday:</… |
|
468 <pre><code class="language-java">public void function(Weekday weekday){ |
|
469 //do stuff |
|
470 } |
|
471 |
|
472 // later on we call it |
|
473 function(Weekday.TUESDAY); |
|
474 </code></pre> |
|
475 <p>This will mean that a user can only pass in one of the values defined… |
|
476 <ul> |
|
477 <li>No risk of the user accidentally typing a wrong input or a malicious… |
|
478 <li>The user knows what he needs to pass in by just looking at the signa… |
|
479 <li>Another benefit over the previous two methods is that the enum types… |
|
480 <li>Using enums opens the door for using EnumSet and EnumMap, two type s… |
|
481 </ul> |
|
482 <pre><code class="language-java">//obsolete idiom |
|
483 public class Renderer{ |
|
484 public static final int COLOR_RED = 1; |
|
485 public static final int COLOR_BLUE = 2; |
|
486 public static final int COLOR_ORANGE = 4; |
|
487 public static final int COLOR_GREEN = 8; |
|
488 |
|
489 public void draw(int colors){ |
|
490 // draw |
|
491 } |
|
492 } |
|
493 </code></pre> |
|
494 <p>Calling the draw function for colors blue and red would be something … |
|
495 <pre><code class="language-java">renderer.draw(COLOR_RED | COLOR_BLUE); |
|
496 </code></pre> |
|
497 <p>With an EnumMap you do not have to apply any of those tricks, things … |
|
498 <pre><code class="language-java">public class Renderer{ |
|
499 public enum Color{RED, BLUE, GREEN, ORANGE} |
|
500 |
|
501 public void draw(Set<Color> colors){ |
|
502 //draw |
|
503 } |
|
504 } |
|
505 </code></pre> |
|
506 <p>We now can call the draw method like this:</p> |
|
507 <pre><code class="language-java">renderer.draw(EnumSet.of(Color.RED, Col… |
|
508 </code></pre> |
|
509 <ul> |
|
510 <li>Enum values are by definition the only instances created of the enum… |
|
511 <li>It helps the compiler identify attempts to compare incompatible type… |
|
512 </ul> |
|
513 <pre><code class="language-java">enum Weekday {MONDAY, TUESDAY, WEDNESDA… |
|
514 enum Color{BLACK, WHITE}; |
|
515 |
|
516 if(Color.BLACK.equals(Weekday.Monday); // does not throw a compile error… |
|
517 if(Color.BLACK == Weekday.Monday); // does not compile because the compi… |
|
518 </code></pre> |
|
519 <p>So to recap, if your function or logic needs to use a parameter or va… |
|
520 <!--kg-card-end: markdown--><figure class="kg-card kg-image-card"><img s… |
|
521 <!--kg-card-end: markdown--><!--kg-card-begin: markdown--><p>The singlet… |
|
522 The classical best practice approach is to use something like the follow… |
|
523 <pre><code class="language-java">public class Singleton{ |
|
524 private static final Singleton INSTANCE = new Singleton(); |
|
525 |
|
526 private Singleton(){}; |
|
527 public static Singleton getInstance(){ |
|
528 return INSTANCE; |
|
529 } |
|
530 public void doSomething(){ |
|
531 //do stuff |
|
532 } |
|
533 |
|
534 //other methods ... |
|
535 } |
|
536 </code></pre> |
|
537 <p>While this works, there are some issue:</p> |
|
538 <ul> |
|
539 <li>If you want your singleton class to be serializable you need not onl… |
|
540 <li>The class could still be instantiated with a new instance through th… |
|
541 </ul> |
|
542 <p>In light of these issues Joshua Bloch recommends, in his famous book … |
|
543 <p>So our example from above would become:</p> |
|
544 <pre><code class="language-java">public enum Singleton{ |
|
545 INSTANCE; |
|
546 |
|
547 public void doSomething(){ |
|
548 // do stuff |
|
549 } |
|
550 |
|
551 // other methods |
|
552 } |
|
553 </code></pre> |
|
554 <p>First of all this looks a lot cleaner right? Now how does this solve … |
|
555 <ul> |
|
556 <li>I will not enter in all the details of how serialization in Java wor… |
|
557 <li>The enum type actually extends the java Enum class. The reason that … |
|
558 </ul> |
|
559 <pre><code class="language-java">if ((clazz.getModifiers() & Modifie… |
|
560 throw new IllegalArgumentException("Cannot reflectively create … |
|
561 </code></pre> |
|
562 <p>So as a best practice, unless one of the caveats from above applies t… |
|
563 <!--kg-card-end: markdown--><figure class="kg-card kg-image-card"><img s… |
|
564 <p>One of the latest things I realized an enum is actually really useful… |
|
565 <p>Lets have a quick recap of the pattern: The Strategy Pattern defines … |
|
566 <p>If that definition sounds to abstract let's showcase its classic… |
|
567 <p>First we need to identify a case where we could apply this pattern:<b… |
|
568 Let us imagine we have a bar and since we want to attract customers we h… |
|
569 <ul> |
|
570 <li>we have the normal hours where clients are charged the full price of… |
|
571 <li>we have the morning happy hour where clients are charged 0.5 of what… |
|
572 <li>we have the afternoon happy hour where clients are charged 0.75 of w… |
|
573 </ul> |
|
574 <p>So we define an interface that encapsulates this logic(don't eve… |
|
575 <pre><code class="language-java">interface BillingStrategy{ |
|
576 double bill(double rawPrice); |
|
577 } |
|
578 </code></pre> |
|
579 <p>Then we define different classes that implement the <em>BillingStrate… |
|
580 <pre><code class="language-java">public MorningHappyHourBilling implemen… |
|
581 double bill(double rawPrice){ |
|
582 return rawPrice * 0.5; |
|
583 } |
|
584 } |
|
585 |
|
586 public EveningHappyHourBilling implements BillingStrategy{ |
|
587 double bill(double rawPrice){ |
|
588 return rawPrice * 0.75; |
|
589 } |
|
590 } |
|
591 |
|
592 public FullPriceBilling implements BillingStrategy{ |
|
593 double bill(double rawPrice){ |
|
594 return rawPrice ; |
|
595 } |
|
596 } |
|
597 </code></pre> |
|
598 <p>Then we define a <em>BillCalculator</em> that would be used by the ba… |
|
599 <pre><code class="language-java">BillCalculator { |
|
600 private BillingStrategy billingStrategy = new FullPriceBilling() ; |
|
601 |
|
602 public void setBillingStrategy(BillingStrategy billingStrategy){ |
|
603 this.billingStrategy = billingStrategy; |
|
604 } |
|
605 |
|
606 public void printBill(int price, String customer){ |
|
607 System.out.format("Bill for customer %s is %f", custom… |
|
608 } |
|
609 } |
|
610 </code></pre> |
|
611 <p>As you can see, now the hypothetical <em>Bar</em> class when using th… |
|
612 <p>Now you might say: "this is nice and all, but it brings quite so… |
|
613 <ul> |
|
614 <li>we have to define a new interface</li> |
|
615 <li>we need to define a new class for each possible strategy,</li> |
|
616 </ul> |
|
617 <p>You are right, usually thats the tradeoff when using design patterns,… |
|
618 <p>Instead of defining an interface, we will define an enum as the type … |
|
619 <pre><code class="language-java">public enum BillingStrategy{ |
|
620 MORNING_HAPPY_HOUR{ |
|
621 @Override |
|
622 public double bill(double price){ |
|
623 return rawPrice * 0.5; |
|
624 } |
|
625 }, |
|
626 AFTERNOON_HAPPY_HOUR{ |
|
627 @Override |
|
628 public double bill(double price){ |
|
629 return rawPrice * 0.75; |
|
630 } |
|
631 }, |
|
632 FULL_PRICE{ |
|
633 @Override |
|
634 public double bill(double price){ |
|
635 return rawPrice; |
|
636 } |
|
637 } |
|
638 |
|
639 public abstract double bill(double price); |
|
640 } |
|
641 </code></pre> |
|
642 <p>Now we can redefine our BillCalculator like this:</p> |
|
643 <pre><code class="language-java">BillCalculator { |
|
644 private BillingStrategy billingStrategy = BillingStrategy.FULL_PRICE; |
|
645 |
|
646 public void setBillingStrategy(BillingStrategy billingStrategy){ |
|
647 this.billingStrategy = billingStrategy; |
|
648 } |
|
649 |
|
650 public void printBill(int price, String customer){ |
|
651 System.out.format("Bill for customer %s is %f", custom… |
|
652 } |
|
653 } |
|
654 </code></pre> |
|
655 <p>A lot cleaner right?</p> |
|
656 <p>As an added bonus, if you are familiar with the State pattern you kno… |
|
657 <!--kg-card-end: markdown--><figure class="kg-card kg-image-card"><img s… |
|
658 <p>That is all I have for now to share and I hope at least some of you d… |
|
659 <p>If you have some other great use cases for enums or some insights abo… |
|
660 <p>If you enjoyed the article you can subscribe or like our facebook pag… |
|
661 <a href="https://www.facebook.com/pg/banterly.net/posts/">https://www.fa… |
|
662 <!--kg-card-end: markdown-->]]></content:encoded></item><item><title><![… |
|
663 <p>"Success is getting what you want, happiness is wanting what you… |
|
664 </blockquote> |
|
665 <p>A trend that started in companies for a few years now has been for ma… |
|
666 <img src="https://www.banterly.net/content/images/2019/01/post2-1.jpg" a… |
|
667 </blockquote> |
|
668 <p>A trend that started in companies for a few years now has been for ma… |
|
669 <ul> |
|
670 <li>Why the hell would companies care about developer happiness?</li> |
|
671 <li>What would actually make a developer happy?</li> |
|
672 </ul> |
|
673 <!--kg-card-end: markdown--><figure class="kg-card kg-image-card"><img s… |
|
674 <p>The ideas expressed will probably be biased towards the western socie… |
|
675 <p>If anyone wants to express some insights from different perspectives … |
|
676 With this small disclaimer in place lets see what we have here.</p> |
|
677 <!--kg-card-end: markdown--><!--kg-card-begin: markdown--><h2 id="whydev… |
|
678 <p>First question you may have is: why am I talking about developer happ… |
|
679 <p>First of all, development is my profession right now, so I know most … |
|
680 <p>Secondly, the thing is that in general companies do not care that muc… |
|
681 The reason why developers are these days in the privileged position of c… |
|
682 <!--kg-card-end: markdown--><figure class="kg-card kg-image-card"><img s… |
|
683 <!--kg-card-end: markdown--><!--kg-card-begin: markdown--><h2 id="thecos… |
|
684 <p>So why would a company care if it has a high turnover rate, cant they… |
|
685 <!--kg-card-end: markdown--><figure class="kg-card kg-image-card"><img s… |
|
686 <h4 id="directcosts">Direct costs:</h4> |
|
687 <ul> |
|
688 <li>Recruiter fees - when using external recruiters their fee is usually… |
|
689 <li>Advertising the open position on different channels like job website… |
|
690 <li>In some cases external training for the new employee.</li> |
|
691 <li>Travel expenses if the candidate is brought in from a foreign countr… |
|
692 </ul> |
|
693 <h4 id="indirectcosts">Indirect costs</h4> |
|
694 <ul> |
|
695 <li>Loss of productivity caused by the team having one less member.</li> |
|
696 <li>Loss of productivity caused by team members interviewing candidates.… |
|
697 <li>Even after a good candidate is found, there will be extra loss of pr… |
|
698 <li>A high turnover rate also impacts the morale of the other employees … |
|
699 <li>A place with a high turnover rate may become infamous in the job mar… |
|
700 </ul> |
|
701 <!--kg-card-end: markdown--><!--kg-card-begin: markdown--><h2 id="whatca… |
|
702 <h4 id="numbersanddata">Numbers and data</h4> |
|
703 <p>Some companies may still not look seriously at the problem of employe… |
|
704 <h4 id="theexitinterview">The exit interview</h4> |
|
705 <p>Secondly they should have in place the so called exit interviews: a t… |
|
706 <p>This activity should be carefully planned since it is easy to gather … |
|
707 <!--kg-card-end: markdown--><figure class="kg-card kg-image-card"><img s… |
|
708 <p>The exit interview is useful not only to find causes of dissatisfacti… |
|
709 <h4 id="awareness">Awareness</h4> |
|
710 <p>Of course another action point would be to have a pulse of all employ… |
|
711 <!--kg-card-end: markdown--><!--kg-card-begin: markdown--><h2 id="whatbr… |
|
712 <!--kg-card-end: markdown--><figure class="kg-card kg-image-card"><img s… |
|
713 <h3 id="money">Money</h3> |
|
714 <p>Lets first get rid of the elephant in the room. Usually when companie… |
|
715 <p>There are a couple of points to be made here. First is that some peop… |
|
716 <!--kg-card-end: markdown--><figure class="kg-card kg-image-card"><img s… |
|
717 <p>Of course there are companies who just cant afford to pay as much mon… |
|
718 <p>Another aspect worth mentioning is that even if an employee is satisf… |
|
719 <p>One last point regarding this topic is that an increase in salary is … |
|
720 <p>I guess there is more to say about this aspect so let me know in the … |
|
721 <!--kg-card-end: markdown--><!--kg-card-begin: markdown--><h3 id="manage… |
|
722 <p>In the end probably most of the other subjects can be tied to this on… |
|
723 <p>For a developer there are two aspects to this topic</p> |
|
724 <ul> |
|
725 <li><strong>his direct manager</strong> - the one to whom he directly re… |
|
726 <li><strong>upper management</strong> - the ones that control the compan… |
|
727 </ul> |
|
728 <!--kg-card-end: markdown--><figure class="kg-card kg-image-card"><img s… |
|
729 <p>This relationship is very important since, for a developer, his direc… |
|
730 Because of this, when talking about loyalty, the developer will most of … |
|
731 <p>An employee wants to feel appreciated, trusted and cared for by the c… |
|
732 <p>In a lot of cases, what the employee wants will go against the desire… |
|
733 <p>In Daniel Pinks book <em><strong>Drive</strong></em> it is argued tha… |
|
734 <ul> |
|
735 <li>Autonomy - Everyone wants to express himself and have a degree of fr… |
|
736 <li>Mastery - developers want to get better at what they do and need the… |
|
737 <li>Purpose - Everyone needs a purpose for what they are doing. If in a … |
|
738 </ul> |
|
739 <!--kg-card-end: markdown--><figure class="kg-card kg-image-card"><img s… |
|
740 <h4 id="uppermanagement">Upper management</h4> |
|
741 <p>No matter how hard the direct manager tries, if the people in control… |
|
742 <p>One of the most cited problems from developers perspective about big … |
|
743 <!--kg-card-end: markdown--><!--kg-card-begin: markdown--><h3 id="benefi… |
|
744 <p>Benefits are an excellent way to provide extra value to employees in … |
|
745 Another thing is that some benefits scale better than salary increases: … |
|
746 <!--kg-card-end: markdown--><!--kg-card-begin: markdown--><h3 id="thelis… |
|
747 <!--kg-card-end: markdown--><figure class="kg-card kg-image-card"><img s… |
|
748 <p>Since this article became longer than I wanted I will leave you with … |
|
749 <ul> |
|
750 <li>Team events, not only company events - team events are usually more … |
|
751 <li>Minimal bureaucracy - No need for 5 committees approval for each sma… |
|
752 <li>Communication and interaction with customers - it brings a lot of jo… |
|
753 <li>Flexible schedule - no hard enforced scheduled working hours, allow … |
|
754 <li>Good tools - The easier it is to use the tools required to do the jo… |
|
755 <li>Office where you can focus when you work. That is why a lot of devel… |
|
756 <li>Properly equipped office: 2 monitors(or 1 big one), a nice chair, a … |
|
757 <li>Good work life balance - when developers start having families this … |
|
758 <li>Management transparency - clear communications on why certain decisi… |
|
759 <li>Clear responsibilities of persons in the company and clear examples … |
|
760 <li>Investment in human resources</li> |
|
761 </ul> |
|
762 <!--kg-card-end: markdown-->]]></content:encoded></item><item><title><![… |
|
763 <p>"Conceal a flaw, and the world will imagine the worst" - Ma… |
|
764 </blockquote> |
|
765 <p>In my <a href="https://www.banterly.net/2016/12/31/blockchain-beyond-… |
|
766 <p>Today I want to talk about something else, about a realization that I… |
|
767 <h2 id="shortblockchainrecap">Short blockchain recap</h2> |
|
768 <p>In case you were too lazy to go to any of the resources indicated abo… |
|
769 <p><img src="https://www.banterly.net/content/images/2018/07/Capture.PNG… |
|
770 <a href="https://medium.com/creativeblockchain/the-blockchain-illustrate… |
|
771 <p>The main idea of blockchain is that of decentralization, more specifi… |
|
772 <p>Truth be told, there are <strong>a lot</strong> of problems with bloc… |
|
773 <ul> |
|
774 <li><strong>No proven use cases</strong> - even as a currency it arguabl… |
|
775 <li><strong>No proven scalability solution</strong> - a few solutions ar… |
|
776 <li><strong>No proven solution for private data storage</strong> - there… |
|
777 <li><strong>The tendency of blockchain networks to become centralized</s… |
|
778 </ul> |
|
779 <h2 id="decentralizationatadisadvantage">Decentralization at a disadvant… |
|
780 <p>Actually, arguably the only success stories in the blockchain world, … |
|
781 <p>The only advantage they could claim is that they operate in a trustle… |
|
782 <p>I am not saying decentralization is bad, just that centralized system… |
|
783 The internet itself, which was considered the go-to model of a decentral… |
|
784 <h2 id="beingoptimisticdidnothelp">Being optimistic did not help</h2> |
|
785 <p>Even with all this problems being evident to me, I wanted to ignore t… |
|
786 It is true that this money also attracted a lot of scammers who got rich… |
|
787 <p><img src="https://www.banterly.net/content/images/2018/07/there-amp-0… |
|
788 <p>I realized that even when ignoring all these issues, there is one pro… |
|
789 <h2 id="thehypegeneratingpromise">The hype-generating promise</h2> |
|
790 <p>Let us assume we have the perfect blockchain system: scalable, fast,… |
|
791 <p>I am here to tell you that things are not so black and white. It is a… |
|
792 <p><img src="https://www.banterly.net/content/images/2018/07/thecakeisal… |
|
793 <h2 id="thenotsohypegeneratingtruth">The not so hype-generating truth</h… |
|
794 <p>My guess is that this misconception comes from the fact that the tech… |
|
795 <p>But if we think in terms of the distributed ledger that is constructe… |
|
796 <p><img src="https://www.banterly.net/content/images/2018/07/9wsxhj0rhst… |
|
797 <a href="https://www.reddit.com/r/Bitcoin/comments/78g5k2/how_bitcoin_fo… |
|
798 <p>This leads me to the following statement which I think everyone needs… |
|
799 <blockquote> |
|
800 <p>The blockchain distributed ledger is not immutable, it is just a coll… |
|
801 </blockquote> |
|
802 <h2 id="decentralizationhelps">Decentralization helps...</h2> |
|
803 <p>Following this rule, we can see why private blockchains (all miners c… |
|
804 <p>That is why most people will tell you it is important for the majorit… |
|
805 <h2 id="theissueemerges">The issue emerges</h2> |
|
806 <p>We need to realize that ultimately this ledger's underlying infr… |
|
807 <p>That is all fine until we realize that this effect may intersect with… |
|
808 <h2 id="historyalreadytaughtus">History already taught us</h2> |
|
809 <p>You may say that this is all hypothetical and the chances of this act… |
|
810 <p><img src="https://www.banterly.net/content/images/2018/07/2ewqau.jpg"… |
|
811 <p>Short summary of what happenened then:</p> |
|
812 <ul> |
|
813 <li>The DAO is setup on the Ethereum blockchain network.</li> |
|
814 <li>The DAO gathers from its crowdsale 150 million dollars worth of ethe… |
|
815 <li>A hacker takes 50 million dollars worth of ether from the DAO using … |
|
816 <li>In fear of Ethereum losing further investors and to maintain the val… |
|
817 </ul> |
|
818 <p>The reason why I put "decides" between quotes is because th… |
|
819 <h2 id="thefatalflaw">The fatal flaw</h2> |
|
820 <p>With the previous example in mind I hope you realize, the same way I … |
|
821 <p><img src="https://www.banterly.net/content/images/2018/07/1526884_555… |
|
822 <p>If you think about it, this does not sound like the kind of decision … |
|
823 <p>...except that is exactly on what blockchain systems are based on.<br> |
|
824 And this is the <em><strong>fatal flaw</strong></em> of blockchain.</p> |
|
825 <!--kg-card-end: markdown-->]]></content:encoded></item><item><title><![… |
|
826 <ol> |
|
827 <li>I was in the process of changing jobs in that period so it took quit… |
|
828 <li>I was working on a project that I am finally proud to announce is li… |
|
829 </ol> |
|
830 <p>After I held a guest lecture at my former master program on the topic… |
|
831 <p>After more than 4 months of work, I am proud to present:</p> |
|
832 <h2 id="masteringblockchainbeyondcryptomania">Mastering blockchain - Bey… |
|
833 <iframe width="560" height="315" src="https://www.youtube.com/embed/SBdw… |
|
834 <p>Since you are a reader of mine, I will offer you special limited (100… |
|
835 <a href="https://www.udemy.com/mastering-blockchain-beyond-cryptomania/?… |
|
836 <p>Can't wait to see you on the course and have your feedback.</p> |
|
837 <!--kg-card-end: markdown-->]]></content:encoded></item><item><title><![… |
|
838 <p><img src="https://www.banterly.net/content/images/2017/07/download-1.… |
|
839 <p>I was just busy in the last months with multiple things, but I am pre… |
|
840 <p>In</p>]]></description><link>https://www.banterly.net/2017/07/23/im-n… |
|
841 <p><img src="https://www.banterly.net/content/images/2017/07/download-1.… |
|
842 <p>I was just busy in the last months with multiple things, but I am pre… |
|
843 <p>In the meantime you can now follow me on my new twitter account and I… |
|
844 <iframe width="560" height="315" src="https://www.youtube.com/embed/K1b8… |
|
845 <p>"If something doesn't make sense it means that one of your … |
|
846 </blockquote> |
|
847 <p>If you want to present to your friend a problem that he will probably… |
|
848 <p>"If something doesn't make sense it means that one of your … |
|
849 </blockquote> |
|
850 <p>If you want to present to your friend a problem that he will probably… |
|
851 <p>Of course the previous paragraph alludes to the (in)famous Monty Hall… |
|
852 <p><img src="https://www.banterly.net/content/images/2017/02/MHDealPromo… |
|
853 <p>It is renowned not only because of its counter-intuitive answer, but … |
|
854 <blockquote> |
|
855 <p><em>May I suggest that you obtain and refer to a standard textbook on… |
|
856 </blockquote> |
|
857 <blockquote> |
|
858 <p><em>Maybe women look at math problems differently than men.</em> - Do… |
|
859 </blockquote> |
|
860 <blockquote> |
|
861 <p><em>I am sure you will receive many letters on this topic from high s… |
|
862 </blockquote> |
|
863 <p>I am sure everyone who tried to present this problem to their acquain… |
|
864 <p>What I will do in this article is present the problem and answer it. … |
|
865 <h3 id="themontyhallproblem">The Monty Hall Problem</h3> |
|
866 <p>The story goes like this:</p> |
|
867 <p><img src="https://www.banterly.net/content/images/2017/02/Capture2.PN… |
|
868 <p><img src="https://www.banterly.net/content/images/2017/02/Capture.PNG… |
|
869 <p><img src="https://www.banterly.net/content/images/2017/02/Capture-1.P… |
|
870 <p><img src="https://www.banterly.net/content/images/2017/02/Capture-2.P… |
|
871 <p>This is it. The famous Monty Hall problem resumes to the simple quest… |
|
872 <p>Think of what you would do and go on and read the next of the article… |
|
873 <h3 id="thesolution">The solution</h3> |
|
874 <p><img src="https://www.banterly.net/content/images/2017/02/359b162052a… |
|
875 Maybe surprisingly for some, the answer is that it is always better to s… |
|
876 <h3 id="explanationsranked">Explanations Ranked</h3> |
|
877 <p>I will next rank all the explanations that I am aware of. Please post… |
|
878 <h4 id="5informationmatters">5. Information Matters</h4> |
|
879 <p>Many people have the misconception that since there are two doors, th… |
|
880 <p>One of the sources for this mistake is that people disregard the fact… |
|
881 <h4 id="4takeallpossiblecases">4. Take all possible cases</h4> |
|
882 <p>An easy way to explain this will be to ask the non believer to take a… |
|
883 <p><img src="https://www.banterly.net/content/images/2017/02/Capture-3.P… |
|
884 <p>As you can see, if you do not switch, you can only win if you initial… |
|
885 <h4 id="3multipledoors">3. Multiple doors</h4> |
|
886 <p>This explanation is where most of the people realize that they were a… |
|
887 <h4 id="2tryityourself">2. Try it yourself</h4> |
|
888 <p>Another great way to convince you of the truth is to try this experim… |
|
889 <h4 id="1doingthemath">1. Doing the math</h4> |
|
890 <p>Now we get to the serious part.</p> |
|
891 <p>As a warning, skip this part if you are not a fan of probabilities an… |
|
892 <p><img src="https://www.banterly.net/content/images/2017/02/14608107_11… |
|
893 This is actually not trivial, even though it does look like a very simpl… |
|
894 <p>We will use <a href="https://en.wikipedia.org/wiki/Random_variable">r… |
|
895 <ul> |
|
896 <li>D: the the door containing the car.</li> |
|
897 <li>P: the first door selected by the player.</li> |
|
898 <li>H: the door opened by the host.</li> |
|
899 <li>X: the final door selected by the player.</li> |
|
900 </ul> |
|
901 <p>Since each variables will represent a door, they can only have as pos… |
|
902 <p>We will now impose some restrictions based on some common sense:</p> |
|
903 <ul> |
|
904 <li>The first thing you will notice is that the host cannot open a door … |
|
905 <li>The second thing to notice, and this is very important, is that the … |
|
906 </ul> |
|
907 <p>It is fair to assume that the car is randomly hidden behind one of th… |
|
908 <p>\[P(D = i)=\frac{1}{3}\ for\ i∈\{1,2,3\} \]</p> |
|
909 <p>The player will first choose randomly a door, since he has no informa… |
|
910 \[P(P = j)=\frac{1}{3}\ for\ j∈\{1,2,3\} \]</p> |
|
911 <p>Next we define the conditional density function of the door the host … |
|
912 <p>\[<br> |
|
913 P(H = k ∣ D = i, P = j) = \left\{<br> |
|
914 \begin{array}{ll}<br> |
|
915 1,\ i≠j,i≠k,k≠j \\<br> |
|
916 \frac{1}{2},\ i=j,k≠i \\<br> |
|
917 0,\ k=i,k=j<br> |
|
918 \end{array}<br> |
|
919 \right. for\ i,j,k∈\{1,2,3\}<br> |
|
920 \]</p> |
|
921 <p>The probability density function of the player's second choice i… |
|
922 <ul> |
|
923 <li>If the player never switches, <em><strong>s=0</strong></em></li> |
|
924 <li>If the player always switches, <em><strong>s=1</strong></em></li> |
|
925 </ul> |
|
926 <p>Taking all these facts into account we get the following:</p> |
|
927 <p>\[<br> |
|
928 P(X = l ∣ P = j, H = k) = \left\{<br> |
|
929 \begin{array}{ll}<br> |
|
930 s,\ l≠j,l≠k,k≠j \\<br> |
|
931 1-s,\ l=j,k≠j \\<br> |
|
932 0,\ k=l,k=j<br> |
|
933 \end{array}<br> |
|
934 \right. for\ l,j,k∈\{1,2,3\}\ with\ j≠k<br> |
|
935 \]</p> |
|
936 <p>We will now unite all these functions in one giant one that will be a… |
|
937 <p>\(P(D=i,P=j,H=k,X=l)=<br> |
|
938 P(D=i) \times P(P=j) \times P(H=k∣D=i,P=j) \times P(X=l∣P=… |
|
939 <p>\[i,j,k,l∈\{1,2,3\}\]</p> |
|
940 <p>Remember that the first two terms are constant so the formula above b… |
|
941 <p>\(P(D=i,P=j,H=k,X=l)=<br> |
|
942 \frac{1}{9} \times P(H=k∣D=i,P=j) \times P(X=l∣P=j,H=k)\)<… |
|
943 <p>\[i,j,k,l∈\{1,2,3\}\]</p> |
|
944 <p>We are almost done. The only remaining thing in our setup is to defin… |
|
945 <p>Now it is calculating time. We have to sum the probabilities of all s… |
|
946 <p>\(\frac{1}{9} \times P(H=2∣D=1,P=1) \times P(X=1∣P=1,H=… |
|
947 \(\frac{1}{9} \times P(H=3∣D=1,P=1) \times P(X=1∣P=1,H=3) … |
|
948 \frac{1}{9}\times\frac{1}{2}\times(1-s)=\frac{1-s}{18}\)<br> |
|
949 \(\frac{1}{9} \times P(H=3∣D=1,P=2) \times P(X=1∣P=2,H=3) … |
|
950 \frac{1}{9}\times1\times s=\frac{s}{9}\)<br> |
|
951 \(\frac{1}{9} \times P(H=2∣D=1,P=3) \times P(X=1∣P=3,H=2)=… |
|
952 \frac{1}{9}\times1\times s=\frac{s}{9}\)</p> |
|
953 <p>Added up we get:</p> |
|
954 <p>\(P(D=1,P=j,H=k,X=1)= \frac{1+s}{9}\)</p> |
|
955 <p>But this is equal with the probabilities of the scenarios where D=X=2… |
|
956 <p>\(P(D=X)=\frac{1+s}{3}\)</p> |
|
957 <p>This is expressing the probability of winning the car using the param… |
|
958 <ul> |
|
959 <li>The player never switches: \(P(D=X)=\frac{1}{3}\)</li> |
|
960 <li>The player always switches: \(P(D=X)=\frac{2}{3}\)</li> |
|
961 </ul> |
|
962 <p>As you can see we made the proof that switching is always better than… |
|
963 <p>All I can say is <em><strong>Q.E.D.</strong></em></p> |
|
964 <!--kg-card-end: markdown-->]]></content:encoded></item><item><title><![… |
|
965 I was recently looking through my university days archive (ahh the days … |
|
966 I was recently looking through my university days archive (ahh the days … |
|
967 <p>I will first show the problem. Try to answer it for yourself and post… |
|
968 <h1 id="theproblem">The problem</h1> |
|
969 <p>Assume that we have the following two very simple classes:</p> |
|
970 <pre><code>class Parent { |
|
971 public: |
|
972 virtual void print(){ |
|
973 std::cout<<"I am the parent class"<<std::endl; |
|
974 } |
|
975 }; |
|
976 |
|
977 class Derived : public Parent { |
|
978 public: |
|
979 virtual void print(int x){ |
|
980 std::cout<<"I am the derived class"<<std::endl; |
|
981 } |
|
982 }; |
|
983 </code></pre> |
|
984 <p>What will each of the following two small pieces of code do and why?<… |
|
985 <pre><code>int main(){ |
|
986 Derived *derived=new Derived; |
|
987 derived->print(); |
|
988 return 0; |
|
989 } |
|
990 |
|
991 int main(){ |
|
992 Parent *derived = new Derived; |
|
993 derived->print(); |
|
994 return 0; |
|
995 } |
|
996 </code></pre> |
|
997 <p>That is it. I know that maybe for some of you this is completely obvi… |
|
998 <h1 id="thesolution">The solution</h1> |
|
999 <p><img src="https://www.banterly.net/content/images/2017/01/1i2lo9.jpg"… |
|
1000 <ul> |
|
1001 <li>The first case fails</li> |
|
1002 <li>The second case will print: <em><strong>"I am the parent class&… |
|
1003 </ul> |
|
1004 <p>The first example has to do with the dominance(or name hiding) mechan… |
|
1005 <p>Now the question comes...why didn't the second one also fail, si… |
|
1006 <p>The key here is that name lookup does not start with the actual type … |
|
1007 <p>I hope you found this as interesting as me and see you next time for,… |
|
1008 <!--kg-card-end: markdown-->]]></content:encoded></item><item><title><![… |
|
1009 <p>"Git good" - anonymous</p> |
|
1010 </blockquote> |
|
1011 <p><img src="https://www.banterly.net/content/images/2017/01/git.png" al… |
|
1012 Since everyone these days is becoming a developer, there is a high chanc… |
|
1013 <p>"Git good" - anonymous</p> |
|
1014 </blockquote> |
|
1015 <p><img src="https://www.banterly.net/content/images/2017/01/git.png" al… |
|
1016 Since everyone these days is becoming a developer, there is a high chanc… |
|
1017 <h4 id="gitbisect">Git bisect</h4> |
|
1018 <p>If you are in a well organized development environment, this command … |
|
1019 <img src="https://www.banterly.net/content/images/2017/01/1hfav8.jpg" al… |
|
1020 <p>You are happily developing cool new features for your application whe… |
|
1021 <p>The idea is simple. You pick a commit from history, using <em>git log… |
|
1022 <p>Let's say we have passionate people who want to save awesome son… |
|
1023 <pre><code>[bdl@composer]$cat amazing_lyrics |
|
1024 Oh! When you're down and looking for some cheering up |
|
1025 Then just head right on up to the candy mountain cave |
|
1026 When you get inside you'll find yourself a cheery land |
|
1027 Such a happy and joyful and perky, merry land |
|
1028 They've got lollipops and gummy drops and candy things |
|
1029 Oh so many things that will brighten up your day |
|
1030 It's impossible to wear a frown in candy town |
|
1031 It's the mecca of love, the candy cave |
|
1032 They've got jelly beans and coconuts with little hats |
|
1033 Candy rabbits, chocolate bunnies, it's a wonderland of sweets |
|
1034 Ride the candy train to town and hear the candy band |
|
1035 Candy bells it's a treat as they march across the land |
|
1036 Cherry ribbons stream across the sky into the ground |
|
1037 Turn around |
|
1038 It astounds! |
|
1039 It's a dancing candy tree |
|
1040 In the candy cave imagination runs so free |
|
1041 So now Charlie, please will you go into the cave |
|
1042 </code></pre> |
|
1043 <p>Then you think that you should evolve your setup with some tests. You… |
|
1044 <pre><code>[bdl@composer]$ python check_song.py amazing_lyrics |
|
1045 WOW!! LYRICS DO NOT MATCH WITH THE ORIGINAL!! YOU ARE RUINING A GREAT … |
|
1046 </code></pre> |
|
1047 <p>Disaster!!! There is an error in the lyrics, even tough looking at th… |
|
1048 We checkout the first commit and verify that it is correct(in general se… |
|
1049 <pre><code>[dragos@composer]$git checkout first_verse |
|
1050 [dragos@composer]$python check_song.py amazing_lyrics |
|
1051 GOOD JOB! THE SONG IS INTACT |
|
1052 </code></pre> |
|
1053 <p>Now we know our guilty commit is somewhere in between these ranges an… |
|
1054 <pre><code>[dragos@composer]$git bisect start |
|
1055 [dragos@composer]$git bisect good first_verse |
|
1056 [dragos@composer]$git bisect bad bad_verse |
|
1057 Bisecting: 8 revisions left to test after this (roughly 3 steps) |
|
1058 [9a2b4ea392d81192b3f0971dc9e0388b0827f10d] Adding amazing ninth verse |
|
1059 </code></pre> |
|
1060 <p>You see what happened? After giving the two commits between which we … |
|
1061 <pre><code>[dragos@composer]$python check_song.py amazing_lyrics |
|
1062 GOOD JOB! THE SONG IS INTACT |
|
1063 [dragos@composer]$git bisect good |
|
1064 Bisecting: 4 revisions left to test after this (roughly 2 steps) |
|
1065 [eada803203224f16fb0760255575473ff3353cbc] Adding amazing thirteenth v… |
|
1066 </code></pre> |
|
1067 <p>With this info, git did a checkout on the commit halfway between this… |
|
1068 <pre><code>[dragos@composer]$python check_song.py amazing_lyrics |
|
1069 WOW!! LYRICS DO NOT MATCH WITH THE ORIGINAL!! YOU ARE RUINING A GREAT … |
|
1070 Bisecting: 1 revision left to test after this (roughly 1 step) |
|
1071 [4b9da3dddf2dcaeb11f3e64746e67cf40882e507] Adding amazing eleventh ver… |
|
1072 [dragos@composer]$python check_song.py amazing_lyrics |
|
1073 WOW!! LYRICS DO NOT MATCH!! YOU ARE RUINING THIS GREAT SONG. |
|
1074 [dragos@composer]$git bisect bad |
|
1075 Bisecting: 0 revisions left to test after this (roughly 0 steps) |
|
1076 [634f0ad38519901d7db8885ed67a9c4122f7d756] Adding amazing tenth verse |
|
1077 [dragos@composer]$python check_song.py amazing_lyrics |
|
1078 GOOD JOB! THE SONG IS INTACT |
|
1079 [dragos@composer]$git bisect good |
|
1080 4b9da3dddf2dcaeb11f3e64746e67cf40882e507 is the first bad commit |
|
1081 commit 4b9da3dddf2dcaeb11f3e64746e67cf40882e507 |
|
1082 Author: bad_person <[email protected]> |
|
1083 Date: Fri Jan 13 00:23:04 2017 +0100 |
|
1084 Adding amazing eleventh verse |
|
1085 :100644 100644 6b805f5880efc6b3aca886c33b892a3c54c69bcd |
|
1086 ab327e224638a8bb744a78d9c1985c80bdb8e852 M amazing_lyrics |
|
1087 </code></pre> |
|
1088 <p>In the end we found the guilty commit so now we can see what was the … |
|
1089 <pre><code>[dragos@composer]$git bisect reset 4b9da |
|
1090 Previous HEAD position was 634f0ad... Adding amazing tenth verse |
|
1091 HEAD is now at 4b9da3d... Adding amazing eleventh verse |
|
1092 [dragos@composer]$git diff HEAD^ HEAD |
|
1093 diff --git a/amazing_lyrics b/amazing_lyrics |
|
1094 index 6b805f5..ab327e2 100644 |
|
1095 --- a/amazing_lyrics |
|
1096 +++ b/amazing_lyrics |
|
1097 @@ -7,4 +7,5 @@ Oh so many things that will brighten up your day |
|
1098 It's impossible to wear a frown in candy town |
|
1099 It's the mecca of love, the candy cave |
|
1100 They've got jelly beans and coconuts with little hats |
|
1101 -Candy rats, chocolate bats, it's a wonderland of sweets |
|
1102 +Candy rabbits, chocolate bunnies, it's a wonderland of sweets |
|
1103 +Ride the candy train to town and hear the candy band |
|
1104 </code></pre> |
|
1105 <p>Aha! So someone did not like candy rats and chocolate bats. Now we kn… |
|
1106 <p>In conclusion, this is useful when you know the behavior that changed… |
|
1107 <h4 id="gitblame">Git blame</h4> |
|
1108 <p>This is maybe the most known command on the list, but since I met a l… |
|
1109 <p><em>Git blame</em> annotates your files with information about each l… |
|
1110 <p>As an example we can take the file from our previous section:</p> |
|
1111 <pre><code>[dragos@compser]$git blame amazing_lyrics |
|
1112 ^d5c5a92 (bdl 2017-01-13 00:06:29 +0100 1) Oh! When you're… |
|
1113 fa76d21a (bdl 2017-01-13 00:07:17 +0100 2) Then just head right… |
|
1114 bab5fc16 (bdl 2017-01-13 00:07:58 +0100 3) When you get inside … |
|
1115 b96e74ec (bdl 2017-01-13 00:08:50 +0100 4) Such a happy and joy… |
|
1116 aa5c8716 (bdl 2017-01-13 00:12:05 +0100 5) They've got lol… |
|
1117 2b26aaf7 (bdl 2017-01-13 00:14:48 +0100 6) Oh so many things th… |
|
1118 7e06c9bb (best_guy 2017-01-13 00:15:45 +0100 7) It's impossible… |
|
1119 104cfd46 (best_guy 2017-01-13 00:16:11 +0100 8) It's the mecca … |
|
1120 5e259be9 (bdl 2017-01-13 00:16:53 +0100 9) They've got jel… |
|
1121 b743274c (bad_person 2017-01-13 00:23:04 +0100 10) Candy rabbits, choco… |
|
1122 b743274c (bad_person 2017-01-13 00:23:04 +0100 11) Ride the candy train… |
|
1123 896d4c44 (bdl 2017-01-13 00:25:32 +0100 12) Candy bells it'… |
|
1124 6e788500 (bdl 2017-01-13 00:27:23 +0100 13) Cherry ribbons strea… |
|
1125 33bbe8ef (bdl 2017-01-13 00:28:02 +0100 14) Turn around |
|
1126 1efad606 (bdl 2017-01-13 00:29:47 +0100 15) It astounds! |
|
1127 9352d03d (bdl 2017-01-13 00:30:45 +0100 16) It's a dancing … |
|
1128 140da6b7 (random_guy 2017-01-13 00:31:17 +0100 17) In the candy cave … |
|
1129 eb97f1c2 (bdl 2017-01-13 00:31:52 +0100 18) So now Charlie, plea… |
|
1130 </code></pre> |
|
1131 <p>Looking at this, we could notice that there are two lines modified by… |
|
1132 Another use is if you just don't understand what a piece of code do… |
|
1133 <p><strong>Fun fact #1</strong>: If a commit hash has the <strong>^</str… |
|
1134 <p><strong>Fun fact #2</strong>: Git can track even line movements acros… |
|
1135 <h4 id="gitreflog">Git reflog</h4> |
|
1136 <p>Probably you were told to avoid using <em>git reset --hard</em> becau… |
|
1137 <p><img src="https://www.banterly.net/content/images/2017/01/1hndjf.jpg"… |
|
1138 <p>What you may not know is that there is (mostly) nothing to worry abou… |
|
1139 <p><em>Reflog</em> is a local structure that records where your HEAD and… |
|
1140 <p><strong>Example time!!</strong></p> |
|
1141 <p>Let's look at our current commit history.</p> |
|
1142 <pre><code>[dragos@composer]$git log --pretty=oneline |
|
1143 8ef8a6b18d4c76497a0cd5b0104336f8253d33a4 first commit of checking softw… |
|
1144 eb97f1c20d82226f4d04e96237bf6956fa09e345 Adding amazing eighteenth verse |
|
1145 140da6b784e33367e200349e6da5c0ddc48e7ef8 Adding amazing seventeenth ver… |
|
1146 9352d03d455b4c646f3de91abd2aacd2998f34b8 Adding amazing sixteenth verse |
|
1147 ... |
|
1148 </code></pre> |
|
1149 <p>Just as a reminder: what <em>git reset</em> does is that it moves the… |
|
1150 <pre><code>[dragos@composer]$git reset HEAD^ |
|
1151 [dragos@composer]$git log --pretty=oneline |
|
1152 eb97f1c20d82226f4d04e96237bf6956fa09e345 Adding amazing eighteenth verse |
|
1153 140da6b784e33367e200349e6da5c0ddc48e7ef8 Adding amazing seventeenth ver… |
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1154 9352d03d455b4c646f3de91abd2aacd2998f34b8 Adding amazing sixteenth verse |
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1155 1efad606e509a3eca835678ebf2e9c2fffaae45c Adding amazing fifteenth verse |
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1156 ... |
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1157 </code></pre> |
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1158 <p>We notice that the latest commit from our previous <em>git log</em> o… |
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1159 <p><img src="https://www.banterly.net/content/images/2017/01/Capture3.PN… |
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1160 <p>We realize that actually the commit we reset was actually perfect and… |
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1161 <pre><code>[dragos@composer]$git reflog |
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1162 eb97f1c HEAD@{0}: reset: moving to HEAD^ |
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1163 8ef8a6b HEAD@{1}: commit: first commit of checking software |
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1164 eb97f1c HEAD@{2}: checkout: moving from d5c5a925da0dc687e8a7d5d40111bbd… |
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1165 d5c5a92 HEAD@{3}: checkout: moving from master to first |
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1166 ... |
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1167 </code></pre> |
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1168 <p>The list goes longer, but for our case we are only interested in the … |
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1169 <pre><code>[dragos@composer]$git reset HEAD@{1} |
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1170 [dragos@composer]$git log --pretty=oneline |
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1171 8ef8a6b18d4c76497a0cd5b0104336f8253d33a4 first commit of checking softw… |
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1172 eb97f1c20d82226f4d04e96237bf6956fa09e345 Adding amazing eighteenth verse |
|
1173 140da6b784e33367e200349e6da5c0ddc48e7ef8 Adding amazing seventeenth ver… |
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1174 9352d03d455b4c646f3de91abd2aacd2998f34b8 Adding amazing sixteenth verse |
|
1175 ... |
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1176 </code></pre> |
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1177 <p>As we can see, things are back to normal. So the next time you panic … |
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1178 <p><img src="https://www.banterly.net/content/images/2017/01/download--1… |
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1179 <p><strong>Fun fact #3</strong>: I said before that by default <em>git l… |
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1180 <h4 id="commitranges">Commit ranges</h4> |
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1181 <p>You reached the final section, congratulations for going the extra mi… |
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1182 <p><img src="https://www.banterly.net/content/images/2017/01/download.jp… |
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1183 <p>Here we will see how to specify range of commits using three methods,… |
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1184 <p><img src="https://www.banterly.net/content/images/2017/01/Capture1.PN… |
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1185 <h5 id="doubledot">Double dot</h5> |
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1186 <p>I guess you used this one, even if you did not know fully what it act… |
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1187 <pre><code>[dragos@composer]$git log --pretty=oneline B..F |
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1188 F |
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1189 D |
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1190 </code></pre> |
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1191 <p>So this shows the commits between the range specified without includi… |
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1192 <pre><code>[dragos@composer]$git log --pretty=oneline G..F |
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1193 F |
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1194 D |
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1195 [dragos@composer]$git log --pretty=oneline F..G |
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1196 G |
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1197 E |
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1198 [dragos@composer]$git log --pretty=oneline C..G |
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1199 G |
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1200 E |
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1201 [dragos@composer]$git log --pretty=oneline G..C |
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1202 C |
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1203 </code></pre> |
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1204 <p>If you have not deduced exactly what this does form the previous outp… |
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1205 <p>One useful usage of this is before you want to push your changes to a… |
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1206 <p><code>[dragos@composer]$git log --pretty=oneline origin/master..HEAD<… |
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1207 <p>The output of the above command will represent the commits that you w… |
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1208 <h5 id="multiplebranches">Multiple branches</h5> |
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1209 <p>So the double dot is all fine and cool, but what do we do when we wan… |
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1210 <pre><code>[dragos@composer]$git log --pretty=oneline G..F |
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1211 [dragos@composer]$git log --pretty=oneline ^G F |
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1212 [dragos@composer]$git log --pretty=oneline F --not G |
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1213 </code></pre> |
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1214 <p>And an example with multiple branches:</p> |
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1215 <pre><code>[dragos@composer]$git log --pretty=oneline G --not H F |
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1216 G |
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1217 </code></pre> |
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1218 <h5 id="tripledot">Triple dot</h5> |
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1219 <p>The last method that we are covering for specifying commit ranges is … |
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1220 <p>Last example and you can go on with your life:</p> |
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1221 <pre><code>[dragos@composer]$git log --pretty=oneline C...G |
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1222 49a59058100707187ac6e8980e77e45e57785407 G |
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1223 4f1615031ededc27944ed43f4fc410b69a637919 E |
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1224 b73244c413956a356ed5076b5b87f087d978ba2f C |
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1225 </code></pre> |
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1226 <h4 id="goodbye">Goodbye</h4> |
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1227 <p>Thats it guys, I hope you learnt at least one thing from this and als… |
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1228 <img src="https://www.banterly.net/content/images/2017/01/1ho2ql.jpg" al… |
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1229 <!--kg-card-end: markdown-->]]></content:encoded></item><item><title><
