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28 Mar 2014 23:23:05 UTC
- Distribution: UNIVERSAL-can
- Module version: 1.20140328
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Bus factor: 1- 92.78% Coverage
- License: perl_5
- Perl: v5.8.0
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NAME
UNIVERSAL::can - work around buggy code calling UNIVERSAL::can() as a function
SYNOPSIS
To use this module, simply:
use UNIVERSAL::can;
DESCRIPTION
The UNIVERSAL class provides a few default methods so that all objects can use them. Object orientation allows programmers to override these methods in subclasses to provide more specific and appropriate behavior.
Some authors call methods in the UNIVERSAL class on potential invocants as functions, bypassing any possible overriding. This is wrong and you should not do it. Unfortunately, not everyone heeds this warning and their bad code can break your good code.
This module replaces
UNIVERSAL::can()
with a method that checks to see if the first argument is a valid invocant has its owncan()
method. If so, it gives a warning and calls the overridden method, working around buggy code. Otherwise, everything works as you might expect.Some people argue that you must call
UNIVERSAL::can()
as a function because you don't know if your proposed invocant is a valid invocant. That's silly. Useblessed()
from Scalar::Util if you want to check that the potential invocant is an object or call the method anyway in aneval
block and check for failure (though check the exception returned, as a poorly-writtencan()
method could break Liskov and throw an exception other than "You can't call a method on this type of invocant").Just don't break working code.
AUTHOR
chromatic,
<chromatic@wgz.org>
BUGS
Please report any bugs or feature requests to
bug-universal-can@rt.cpan.org
, or through the web interface at http://rt.cpan.org/NoAuth/ReportBug.html?Queue=UNIVERSAL-can. This will contact me, hold onto patches so I don't drop them, and will notify you of progress on your request as I make changes.ACKNOWLEDGEMENTS
Inspired by UNIVERSAL::isa by Yuval Kogman, Autrijus Tang, and myself.
Adam Kennedy has tirelessly made me tired by reporting potential bugs and suggesting ideas that found actual bugs.
Mark Clements helped to track down an invalid invocant bug.
Curtis "Ovid" Poe finally provided the inspiration I needed to clean up the interface.
Peter du Marchie van Voorthuysen identified and fixed a problem with calling
SUPER::can
.Daniel LeWarne found and fixed a deep recursion error.
Norbert Buchmüller fixed an overloading bug in blessed invocants.
The Perl QA list had a huge... discussion... which inspired my realization that this module needed to do what it does now.
COPYRIGHT & LICENSE
Copyright (c) 2005 - 2014, chromatic. This module is made available under the same terms as Perl 5.12.
Module Install Instructions
To install UNIVERSAL::can, copy and paste the appropriate command in to your terminal.
cpanm UNIVERSAL::can
perl -MCPAN -e shell install UNIVERSAL::can
For more information on module installation, please visit the detailed CPAN module installation guide.