NAME
   Perl::Snippets - A collection of Perl idioms or short pieces of Perl
   code

VERSION
   This document describes version 0.002 of Perl::Snippets (from Perl
   distribution Perl-Snippets), released on 2019-05-29.

DESCRIPTION
   This distribution catalogs (in its POD pages) various idioms or short
   pieces of code that a Perl programmer usually uses. You can also
   copy-paste them to your code.

   The pieces of code are often too small to refactor into modules, or
   sometimes they have been refactored as modules but you still want to
   "inline" them to avoid adding a dependency. The pieces of code are often
   Perl idioms (patterns of code that are specific to Perl programming),
   but not always.

THE IDIOMS
 Arrays (ARY)
 Arrays / Sorting arrays (ARY/SORT)
  snippet ARY/SORT/1
    my @sorted = map  { $_->[0] }
                 sort { $a->[1] <=> $b->[1] }
                 map  { [$_, gen_key_for($_)] }
                 @ary;

   This is the infamous Schwartzian transform named after Randal Schwartz
   who popularized it during the early days of Perl 5 in 1994. Basically,
   it's a one-statement way to sort an array using a key. Examples of
   functions to generate a key: "length($_)" (to sort by string length),
   "lc($_)" (to do case-insensitive sorting).

   Related documentation:
   <https://en.wikipedia.org/wiki/Schwartzian_transform>

 Hashes (HASH)
 I/O (IO)
 I/O / File I/O (IO/FILE)
  snippet IO/FILE/1
    my $content = do { local $/; <$fh> };

   The above snippet slurps the whole file (which has been opened with
   filehandle $fh) into memory (scalar variable). The "do {}" block
   localizes the effect of $/. If you start from a filename and want to
   open it first:

  snippet IO/FILE/2
    my $content = do { local $/; open my $fh, "<", $filename; <$fh> };

  snippet IO/FILE/3
    my @lines = do { local $/; open my $fh, "<", $filename; <$fh> };

   Like the previous snippet but you get the content as an array of lines.
   Each line still has their terminating newlines. If you want to trim
   those:

  snippet IO/FILE/4
    chomp(my @lines = do { local $/; open my $fh, "<", $filename; <$fh> });

   Related modules: File::Slurper.

   Related documentation: $/ in perlvar.

 Modules (MOD)
  snippet MOD/LOAD/1
    { (my $mod_pm = "$mod.pm") =~ s!::!/!g; require $mod_pm }

   You have a module name in $mod (e.g. "Foo::Bar") and want to
   load/"require" it. You cannot just use "require $mod" because require
   expects its non-bareware argument to be in the form of "Foo/Bar.pm". So
   the above snippet converts $mod to that form.

   This is safer than "eval "use $mod"" or "eval "require $mod"" which work
   but necessitates you to check that $mod does not contain arbitrary and
   dangerous code.

   Related modules: Module::Load

   Related documentation: "require" in perlfunc.

  snippet MOD/LOAD/2
    require Foo::Bar; Foo::Bar->import("baz", "qux");

   The above snippet loads "Foo::Bar" module and imports things from the
   module. It is the run-time equivalent of "use Foo::Bar "baz", "qux";".
   "require Foo::Bar;" itself is the run-time equivalent of "use Foo::Bar
   ();", i.e. loading a module without importing anything from it.

 Process / Child process (PROC/CHLD)
   Some bit-fiddling and logic is needed to extract exit code from $?
   ($CHILD_ERROR). Process::Status makes things easier by presenting you
   with an object that you can query, but if you just want an exit code:

  snippet PROC/CHLD/1
    my ($exit_code, $signal, $core_dump) = ($? < 0 ? $? : $? >> 8, $? & 127, $? & 128);

   This snippet extracts all the information contained in $?: exit code
   (which can be -1 to mean there is no child process being created due to
   an execution error, e.g. "system "non-existent-command""), what signal
   the child process dies from, and whether the child process dumps core.

  snippet PROC/CHLD/2
    my $exit_code = $? < 0 ? $? : $? >> 8.

   This snippets just extracts the exit code of child process (which can be
   -1 to mean that there is no child process being created due to an
   execution error, e.g. "system "non-existent-command"").

   Related modules: Process::Status, Proc::ChildError.

   Related documentation: $? in perlvar.

 Objects (OBJ)
 References (REF)
 Subroutines (SUB)
 Subroutines / subroutine arguments (SUB/ARG)
HOMEPAGE
   Please visit the project's homepage at
   <https://metacpan.org/release/Perl-Snippets>.

SOURCE
   Source repository is at
   <https://github.com/perlancar/perl-Perl-Snippets>.

BUGS
   Please report any bugs or feature requests on the bugtracker website
   <https://rt.cpan.org/Public/Dist/Display.html?Name=Perl-Snippets>

   When submitting a bug or request, please include a test-file or a patch
   to an existing test-file that illustrates the bug or desired feature.

SEE ALSO
   Common Perl idioms (2004) <https://www.perlmonks.org/?node_id=376948>

   The Idioms subchapter in the Modern Perl book.
   <http://modernperlbooks.com/>

   perlsecret

AUTHOR
   perlancar <[email protected]>

COPYRIGHT AND LICENSE
   This software is copyright (c) 2019 by [email protected].

   This is free software; you can redistribute it and/or modify it under
   the same terms as the Perl 5 programming language system itself.

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