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 own "can()" 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.  Use "blessed()" from
       Scalar::Util if you want to check that the potential invocant is an object or call the
       method anyway in an "eval" block and check for failure (though check the exception
       returned, as a poorly-written "can()" 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.