Exporter::ConditionalSubs
version v1.10.1
Allows subroutines to be conditionally exported. If the condition is satisfied, the subroutine will be exported as usual. But if not, the subroutine will be replaced with a stub that gets optimized away by the compiler. When stubbed out, not even the arguments to the subroutine will get evaluated.
This allows for e.g. assertion-like behavior, where subroutine calls can be left in the code but effectively ignored under certain conditions.
First create a module that ISA Exporter::ConditionalSubs:
ISA
package My::Assertions; require Exporter::ConditionalSubs; our @ISA = qw( Exporter::ConditionalSubs ); our @EXPORT = (); our @EXPORT_OK = qw( _assert_non_empty ); sub _assert_non_empty { carp "Found empty value" unless length(shift // '') > 0; }
Then, specify an -if or -unless condition when useing that module:
-if
-unless
use
package My::App; use My::Assertions qw( _assert_non_empty ), -if => $ENV{DEBUG}; use My::MoreAssertions -unless => $ENV{RUNTIME} eq 'prod'; # Coderefs work too: use My::OtherAssertions -if => sub { ... some logic ... }; _assert_non_empty($foo); # this subroutine call might be a no-op
This is a subclass of Exporter and works just like it, with the addition of support for the -if and -unless import arguments.
Exporter::ConditionalSubs - Conditionally export subroutines
Version 1.01
Works like the Exporter import() function, except that it checks for an optional -if or -unless import arg, followed by either a boolean, or a coderef that returns true/false.
import()
If the condition evaluates to true for -if, or false for -unless, then any subs are exported as-is. Otherwise, any subs in @EXPORT_OK are replaced with stubs that get optimized away by the compiler.
@EXPORT_OK
You can specify either -if or -unless, but not both. Croaks if both are specified, or if you specify the same option more than once.
Exporter
B::CallChecker
B::Generate
Larry Leszczynski, <larryl at cpan.org>
<larryl at cpan.org>
Please report any bugs or feature requests at: https://github.com/GrantStreetGroup/Exporter-ConditionalSubs
You can find documentation for this module with the perldoc command.
perldoc Exporter::ConditionalSubs
You can also look for information at:
GitHub
https://github.com/GrantStreetGroup/Exporter-ConditionalSubs
MetaCPAN
https://metacpan.org/pod/Exporter::ConditionalSubs
AnnoCPAN, Annotated CPAN documentation
http://annocpan.org/dist/Exporter-ConditionalSubs
CPAN Ratings
http://cpanratings.perl.org/d/Exporter-ConditionalSubs
Thanks to Grant Street Group http://www.grantstreet.com for funding development of this code.
Thanks to Tom Christiansen (<tchrist@perl.com>) for help with the symbol table hackery.
<tchrist@perl.com>
Thanks to Zefram (<zefram@fysh.org>) for the pointer to his Debug::Show hackery.
<zefram@fysh.org>
Copyright 2015 Grant Street Group
This program is free software; you can redistribute it and/or modify it under the terms of the the Artistic License (2.0). You may obtain a copy of the full license at:
http://www.perlfoundation.org/artistic_license_2_0
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This license includes the non-exclusive, worldwide, free-of-charge patent license to make, have made, use, offer to sell, sell, import and otherwise transfer the Package with respect to any patent claims licensable by the Copyright Holder that are necessarily infringed by the Package. If you institute patent litigation (including a cross-claim or counterclaim) against any party alleging that the Package constitutes direct or contributory patent infringement, then this Artistic License to you shall terminate on the date that such litigation is filed.
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Grant Street Group <developers@grantstreet.com>
This software is Copyright (c) 2015 - 2020 by Grant Street Group.
This is free software, licensed under:
The Artistic License 2.0 (GPL Compatible)
To install Exporter::ConditionalSubs, copy and paste the appropriate command in to your terminal.
cpanm
cpanm Exporter::ConditionalSubs
CPAN shell
perl -MCPAN -e shell install Exporter::ConditionalSubs
For more information on module installation, please visit the detailed CPAN module installation guide.