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יובל קוג'מן (Yuval Kogman)


Check::ISA - DWIM, correct checking of an object's class


        use Check::ISA;

        if ( obj($foo, "SomeClass") ) {

        # instead of one of these methods:
        UNIVERSAL::isa($foo, "SomeClass") # WRONG
        ref $obj eq "SomeClass"; # VERY WRONG
        $foo->isa("SomeClass") # May die
        local $@; eval { $foo->isa("SomeClass") } # too long


This module provides several functions to assist in testing whether a value is an object, and if so asking about its class.


obj $thing, [ $class ]

This function tests if $thing is an object.

If $class is provided, it also tests tests whether $thing->isa($class).

$thing is considered an object if it's blessed, or if it's a GLOB with a valid IO slot (the IO slot contains a FileHandle object which is the actual invocant). This corresponds directly to gv_fetchmethod.

obj_does $thing, [ $class_or_role ]

Just like obj but uses "DOES" in UNIVERSAL instead of "isa" in UNIVERSAL.

"DOES" in UNIVERSAL is just like isa, except it's use is encouraged to query about an interface, as opposed to the object structure. If DOES is not overridden by th ebject, calling it is semantically identical to calling isa.

This is probably reccomended over obj for interoperability, but can be slower on Perls before 5.10.

Note that "DOES" in UNIVERSAL

inv $thing, [ $class_or_role ]

Just like obj_does, but also returns true for classes.

Note that this method is slower, but is supposed to return true for any value you can call methods on (class, object, filehandle, etc).

Look into autobox if you would like to be able to call methods on all values.

obj_can $thing, $method
inv_can $thing, $method

Checks if $thing is an object or class, and calls can on $thing if appropriate.


UNIVERSAL, Params::Util, autobox, Moose, asa


This module is maintained using Darcs. You can get the latest version from http://nothingmuch.woobling.org/code, and use darcs send to commit changes.


Yuval Kogman <nothingmuch@woobling.org>


        Copyright (c) 2008 Yuval Kogman. All rights reserved
        This program is free software; you can redistribute
        it and/or modify it under the same terms as Perl itself.