| UNIVERSAL::isa - Attempt to recover from people calling UNIVERSAL::isa as a function |
UNIVERSAL::isa - Attempt to recover from people calling UNIVERSAL::isa as a function
version 1.20150614
# from the shell
echo 'export PERL5OPT=-MUNIVERSAL::isa' >> /etc/profile
# within your program
use UNIVERSAL::isa;
# enable warnings for all dodgy uses of UNIVERSAL::isa
use UNIVERSAL::isa 'verbose';
Whenever you use isa in the UNIVERSAL manpage as a function, a kitten using the Test::MockObject manpage dies. Normally, the kittens would be helpless, but if they use the UNIVERSAL::isa manpage (the module whose docs you are reading), the kittens can live long and prosper.
This module replaces UNIVERSAL::isa with a version that makes sure that,
when called as a function on objects which override isa, isa will call
the appropriate method on those objects
In all other cases, the real UNIVERSAL::isa gets called directly.
NOTE: You should use this module only for debugging purposes. It does not belong as a dependency in running code.
If the lexical warnings pragma is available, this module will emit a warning
for each naughty invocation of UNIVERSAL::isa. Silence these warnings by
saying:
no warnings 'UNIVERSAL::isa';
in the lexical scope of the naughty code.
After version 1.00, warnings only appear when naughty code calls UNIVERSAL::isa() as a function on an invocant for which there is an overridden isa(). These are really truly active bugs, and you should fix them rather than relying on this module to find them.
To get warnings for all potentially dangerous uses of UNIVERSAL::isa() as a
function, not a method (that is, for all uses of the method as a function,
which are latent bugs, if not bugs that will break your code as it exists now),
pass the verbose flag when using the module. This can generate many extra
warnings, but they're more specific as to the actual wrong practice and they
usually suggest proper fixes.
the Perl::Critic::Policy::BuiltinFunctions::ProhibitUniversalIsa manpage
the UNIVERSAL::can manpage for another discussion of the problem at hand.
the Test::MockObject manpage for one example of a module that really needs to override
isa().
Any decent explanation of OO to understand why calling methods as functions is a staggeringly bad idea.
This software is copyright (c) 2011 by chromatic@wgz.org.
This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.
| UNIVERSAL::isa - Attempt to recover from people calling UNIVERSAL::isa as a function |