UNIVERSAL::can(3pm)   User Contributed Perl Documentation  UNIVERSAL::can(3pm)

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 Buchmller 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.

perl v5.34.0                      2022-10-13               UNIVERSAL::can(3pm)

Czas wygenerowania: 0.00037 sek.

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