in reply to Re^6: Is "ref($class) || $class" a bad thing?
in thread Is "ref($class) || $class" a bad thing?

Because a common idiom used to "solve" the "class or object method?" question, can lead to odd behavior when a constructor is called as a function and not a method.

I disagree:

#!/usr/bin/perl -w

use strict;

use Test::More tests => 2;

package Foo;

sub new
{
    my $class = shift;
    bless {}, $class;
}

sub test
{
    1;
}

package Bar;

sub new
{
    my $class = shift;
    $class    = ref( $class ) || $class;
    bless {}, $class;
}

sub test
{
    1;
}

package main;

sub test
{
    0;
}

my $foo = Foo::new();
ok( $foo->test() );

my $bar = Bar::new();
ok( $bar->test() );

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That's the same behavior regardless of the "class or object?" check. This leads me to conclude that that check has no bearing on the behavior. What leads you to believe otherwise?

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Re^8: Is "ref($class) || $class" a bad thing?
by stvn (Monsignor) on Jul 13, 2004 at 01:39 UTC
    Because a common idiom used to "solve" the "class or object method?" question, can lead to odd behavior when a constructor is called as a function and not a method.
    I disagree:

    How can you disagree with it? Your script proves it. Does not bless {}, ref($class) || $class lead to odd behavior when called as a function (specifically being blessed into main::). Sure it does, and the same goes for bless {}, shift, but that only tells me that both are (maybe) bad, not just bless {}, ref($class) || $class.

    To be honest, I am confused by your argument here. You are comparing bless {}, ref($class) || $class with bless {}, shift, saying that they have the same behavior when called as a function and not a method. I agree with that, I have never disagreed. I didn't bring that second idiom up, you did, and in the end, I just see it as having the same problems as the first idiom.

    I don't think I ever said that "class or object" is the only possible cause of the odd behavior, it is one of them. And I am not sure why you seem to be implying that bless {}, ref($class) || $class and bless {}, shift are my only (?) two options. I guess I am just not understanding what you are trying to say.

    My original point was that practices like bless {}, ref($class) || $class (which includes bless {}, shift) are not really the best since they can create a problem when constructors are called as functions (accidentaly or on purpose).

    What leads you to believe otherwise?

    I don't believe otherwise, I believe that not checking the specifics of $class is (in some cases) bad no matter how you do/don't it.

    -stvn
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