in reply to Re: Calling can method
in thread Calling can method

No no no no,

I can call any static method by ClassName->method. Including 'can' method. I can safely call Test->can('foo'). I have tried that. It works and I use it frequently.

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Re: Re: Re: Calling can method
by merlyn (Sage) on May 30, 2001 at 17:01 UTC
    You can't safely call $x->can('foo') though, although you can always call UNIVERSAL::can($x, 'foo'), which is where the idiom comes from. True, it's overkill for the class case, but for the instance case, it's mandatory.

    -- Randal L. Schwartz, Perl hacker

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      Well, I wonder in what circumstances I cannot call $x->can('foo') safely.

      Only scenario that comes to my mind is when author of class that implements object $x overrides method 'can'. But if such an author would do this, he is supposed to know what he is doing, as 'can' is a well known method together with 'isa'.

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        When can't you call $x->can('foo') safely? When $x can't can(), of course! 
        for $x ('main', undef, \1) {

  if (UNIVERSAL::can($x, 'can')) {

    # ok

    print "can can\n";
    $x->can('foo');
    print "\n";

  } else {

    # error: Can't call method "can" on undefined value/unblessed refe
+rence ...

    print "can't can\n";
    eval { $x->can('foo') };
    print "$@\n";

  }

}

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