/ 
Exporter-ConditionalSubs-1.01
River stage one • 1 direct dependent • 2 total dependents
/ Exporter::ConditionalSubs

NAME

Exporter::ConditionalSubs - Conditionally export subroutines

VERSION

Version 1.01

SYNOPSIS

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:

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:

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.

SUBROUTINES

import

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.

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.

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.

SEE ALSO

Exporter

B::CallChecker

B::Generate

AUTHOR

Larry Leszczynski, <larryl at cpan.org>

BUGS

Please report any bugs or feature requests at: https://github.com/GrantStreetGroup/Exporter-ConditionalSubs

SUPPORT

You can find documentation for this module with the perldoc command.

perldoc Exporter::ConditionalSubs

You can also look for information at:

AUTHOR

Larry Leszczynski, <larryl at cpan.org>

ACKNOWLEDGEMENTS

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.

Thanks to Zefram (<zefram@fysh.org>) for the pointer to his Debug::Show hackery.

LICENSE AND COPYRIGHT

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

Any use, modification, and distribution of the Standard or Modified Versions is governed by this Artistic License. By using, modifying or distributing the Package, you accept this license. Do not use, modify, or distribute the Package, if you do not accept this license.

If your Modified Version has been derived from a Modified Version made by someone other than you, you are nevertheless required to ensure that your Modified Version complies with the requirements of this license.

This license does not grant you the right to use any trademark, service mark, tradename, or logo of the Copyright Holder.

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.

Disclaimer of Warranty: THE PACKAGE IS PROVIDED BY THE COPYRIGHT HOLDER AND CONTRIBUTORS "AS IS' AND WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES. THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT ARE DISCLAIMED TO THE EXTENT PERMITTED BY YOUR LOCAL LAW. UNLESS REQUIRED BY LAW, NO COPYRIGHT HOLDER OR CONTRIBUTOR WILL BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING IN ANY WAY OUT OF THE USE OF THE PACKAGE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.