NAME
Term::Chrome - DSL for colors and other terminal chrome
SYNOPSIS
use Term::Chrome qw<Red Blue Bold Reset Underline Green color>;
# Base color constant and attribute
say Red, 'red text', Reset;
# Composition, using operator overloading
say Red/Blue+Bold, 'red on blue', Reset;
# Undo
say Bold, 'bold', !Bold, 'not bold';
# Extended xterm-256 colors
say color(125) + Underline, 'Purple', Reset;
# Define your own constants
use constant Pink => color 213;
# Use ${} around Chrome expression inside strings
say "normal ${ Red+Bold } RED ${ +Reset } normal";
# Extract components
say( (Red/Blue)->bg, "blue text", (Green+Reset)->flags );
Chromizer: get a closure that applies given chrome before, and undo
after the argument.
# Get an efficient chromizer
my $boldifier = \&{ +Bold };
# Use the chromizer
say $boldifier->("bold text");
# Same as:
say Bold, "bold text", !Bold;
# Short lived chromizers using color literals:
say(&{+Red}('red'));
say(&{ Red/Blue + Bold }('red on blue'));
# Same, but requires perl 5.21.4+
#say(( Red/Blue + Bold )->('red on blue'));
DESCRIPTION
Term::Chrome is a domain-specific language (DSL) for terminal
decoration (colors and other attributes).
In the current implementation stringification to ANSI sequences for
xterm and xterm-256 is hard-coded (which means it doesn't use the
terminfo(5) database), but this gives optimized (short) strings.
Colors and attributes are exposed as objects that have overloading for
arithmetic operators.
EXPORTS
Functions
color(0-255)
Build a Term::Chrome object with the given color number. You can use
this constructor to create your own set of color constants.
For example, color(0) gives the same result as Black (but not the same
object).
Colors
Each of these function return a Chrome object.
* Black: color 0
* Red: color 1
* Green: color 2
* Yellow: color 3
* Blue: color 4
* Magenta: color 5
* Cyan: color 6
* White: color 7
Decoration flags
The exact rendering of each flag is dependent on how the terminal
implements them. For example Underline and Blink may do nothing.
* Bold
* Underline
* Blink
* Reverse
Special flags
* Reset: reset all colors and flags
* ResetFlags: reset (undo) all chrome flags (Bold, Underline, Blink,
Reverse)
* ResetFg: reset (undo) foreground color
* ResetBg: reset (undo) background color
METHODS
Here are the methods on Term::Chrome objects:
fg
Extract the Chrome object of just the foreground color. Maybe undef.
bg
Extract the Chrome object of the just background color. Maybe undef.
flags
Extract a Chrome object of just the decoration flags. Maybe undef.
OVERLOADED OPERATORS
/ (mnemonic: "over")
Combine a foreground color (on the left) with a background color.
Example:
my $red_on_black = Red / Black;
+
Add decoration flags (on the right) to colors (on the left).
Example:
my $bold_red = Red + Bold;
! (negation)
Returns a chrome which is the reverse of chrome to which negation is
applied.
my $reset_foreground = ! Red;
my $reset_colors = ! (Red / Black);
The reverse of Reset, ResetFg, ResetBg, ResetFlags is nothing.
"" (stringification)
Transform the object into a string of ANSI sequences. This is
particularly useful to directly use a Chrome object in a double
quoted string.
${} (scalar dereference)
Same result as "" (stringification). This operator is overloaded
because it is convenient to interpolate Chrome expressions in
double-quoted strings.
Examples:
say "normal ${ +Red } red ${ +Reset }";
say "normal ${ Red + Bold } red ${ +Reset }";
Note that you must force expression parsing context when a Chrome
constant is used alone inside ${ }: ${ +Red } or ${ (Red) } or ${
Red() }. use strict 'vars'; will detect those cases, but you may miss
them in one-liners.
&{} (code dereference, or codulation)
Wrap some text with the given chrome and Reset.
Example:
say Red->("red text");
# Same result as:
say Red, "red text", Reset;
Unfortunately perl had a bug (perl RT#122607
<
https://rt.perl.org/Ticket/Display.html?id=122607>) that makes this
feature not much usable in practice when applied to constants. That
bug is fixed in perl 5.21.4+. On perl < 5.21.4 you have to wrap the
chrome constant in a do {} or use &{}():
say do{ Red }->("red text");
say &{ +Red }("red text");
Codulation can also be used to extract a colorizer sub that will be
more efficient if you use it multiple times:
my $redifier = \&{ Red };
say $redifier->("red text");
BUGS
See the warnings about ${} and &{} above.
REFERENCES
* ISO 6429 / ECMA 48:
https://www.ecma-international.org/publications/files/ECMA-ST/Ecma-048.pdf
(reference for SGR is at page 61, numbered 75 in PDF)
* XTerm Control Sequences:
http://invisible-island.net/xterm/ctlseqs/ctlseqs.html#h2-Functions-using-CSI-_-ordered-by-the-final-character_s_
SEE ALSO
Comments on each modules are opinions of the author.
* Term::ANSIColor: the same basic features (and the others should not
be in Term::ANSIColor itself but in an extension), but with an awful
API I could never even consider to use while keeping my sanity.
* Term::ScreenColor
* PerlIO::via::ANSIColor
* AngelPS1 or
https://github.com/dolmen/angel-PS1: "The Angel's
Prompt" is the project for which Term::Chrome has been built.
AngelPS1::Compiler, the angel-PS1 compiler has special support for
Term::Chrome values.
TRIVIA
Did you know that chartreuse is one of the favorite colors of Larry
Wall?
AUTHOR
Olivier Mengué <
[email protected]>
COPYRIGHT & LICENSE
Copyright © 2013-2018 Olivier Mengué.
This library is free software; you can redistribute it and/or modify it
under the same terms as Perl 5 itself.
