Keyword::Simple(3pm) | User Contributed Perl Documentation | Keyword::Simple(3pm) |
Keyword::Simple - define new keywords in pure Perl
package Some::Module; use Keyword::Simple; sub import { # create keyword 'provided', expand it to 'if' at parse time Keyword::Simple::define 'provided', sub { my ($ref) = @_; substr($$ref, 0, 0) = 'if'; # inject 'if' at beginning of parse buffer }; } sub unimport { # lexically disable keyword again Keyword::Simple::undefine 'provided'; } 'ok'
Warning: This module is still new and experimental. The API may change in future versions. The code may be buggy.
This module lets you implement new keywords in pure Perl. To do this, you need to write a module and call "Keyword::Simple::define" in your "import" method. Any keywords defined this way will be available in the lexical scope that's currently being compiled.
You can modify this scalar in any way you like and after your coderef returns, perl will continue parsing from that scalar as if its contents had been the real source code in the first place.
This module depends on the pluggable keyword API introduced in perl 5.12. Older versions of perl are not supported.
Every new keyword is actually a complete statement by itself. The parsing magic only happens afterwards. This means that e.g. the code in the "SYNOPSIS" actually does this:
provided ($foo > 2) { ... } # expands to ; if ($foo > 2) { ... }
The ";" represents a no-op statement, the "if" was injected by the Perl code, and the rest of the file is unchanged.
This also means your new keywords can only occur at the beginning of a statement, not embedded in an expression.
Keywords in the replacement part of a "s//.../e" substitution aren't handled correctly and break parsing.
There are barely any tests.
After installing, you can find documentation for this module with the "perldoc" command.
perldoc Keyword::Simple
You can also look for information at <https://metacpan.org/pod/Keyword::Simple>.
To see a list of open bugs, visit <https://rt.cpan.org/Public/Dist/Display.html?Name=Keyword-Simple>.
To report a new bug, send an email to "bug-Keyword-Simple [at] rt.cpan.org".
Lukas Mai, "<l.mai at web.de>"
Copyright (C) 2012, 2013 Lukas Mai.
This program is free software; you can redistribute it and/or modify it under the terms of either: the GNU General Public License as published by the Free Software Foundation; or the Artistic License.
See http://dev.perl.org/licenses/ for more information.
2022-10-19 | perl v5.36.0 |