Manual Reference Pages - UNIVERSAL::ISA (3)
UNIVERSAL::isa - Attempt to recover from people calling UNIVERSAL::isa as a function
# from the shell
echo export PERL5OPT=-MUNIVERSAL::isa >> /etc/profile
# within your program
# enable warnings for all dodgy uses of UNIVERSAL::isa
use UNIVERSAL::isa verbose;
Whenever you use isa in UNIVERSAL as a function, a kitten using
Test::MockObject dies. Normally, the kittens would be helpless, but if they
use UNIVERSAL::isa (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.
<B>NOTE:B> 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
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 theyre more specific as to the actual wrong practice and they
usually suggest proper fixes.
UNIVERSAL::can for another discussion of the problem at hand.
Test::MockObject for one example of a module that really needs to override
Any decent explanation of OO to understand why calling methods as functions is
a staggeringly bad idea.
COPYRIGHT AND LICENSE
This software is copyright (c) 2011 by email@example.com.
This is free software; you can redistribute it and/or modify it under
the same terms as the Perl 5 programming language system itself.
|perl v5.20.3 ||UNIVERSAL::ISA (3) ||2015-06-14 |
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