in reply to Re: if (UNIVERSAL::isa($r, ref $l))
in thread if (UNIVERSAL::isa($r, ref $l))

Hey, I edited that.

I really don't see what advantage __PACKAGE__ has over a hardcoded class name except that it's Pythonesquely uglier.

Alright, I can hear dozens of keyboards getting ready to type "What about inheritance, you dope?" Before you get excited, try this little program:

package Foo;

sub new
{
    bless {}, __PACKAGE__;
}   

package Bar;

use vars qw( @ISA );

@ISA = 'Foo';

package main;

my $bar = Bar->new();
print "Bar is a ", ref $bar, "\n";

[download]

Yep, the package into which it's compiled. Nope, not all that useful. Pity.

Update: Okay, if you don't like hardcoding the class name, there's an advantage. The Class module gets rid of the ugliness. That's kinda useful.

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Re: Re: Re: if (UNIVERSAL::isa($r, ref $l))
by demerphq (Chancellor) on Jul 24, 2003 at 07:25 UTC

    You edited it did you? I see, shame on you. ;-)

    I really don't see what advantage __PACKAGE__ has over a hardcoded class name except that it's Pythonesquely uglier.

    The advantage is that using __PACKAGE__ works, whereas as written it fails the empty subclass test because of the ref $l thing 

    use Number::Fraction;
package Number::Fraction::Foo;
use base qw/Number::Fraction/;
1;
package Number::Fraction::Bar;
use base qw/Number::Fraction/;
1;

my $n=Number::Fraction->new(1,4);
my $f=Number::Fraction::Foo->new(1,4);
my $b=Number::Fraction::Bar->new(1,4);

print $n+$f,$/;
print $n+$b,$/;
print $f+$n,$/;
print $b+$n,$/;
print $f+$b,$/;
print $b+$f,$/;
__END__
Can't add a Number::Fraction::Foo to a Number::Fraction::Foo at D:\per
+l\devlib\/Number/Fraction.pm line 119
    Number::Fraction::add('1/4', '1/4', '') called at D:\Temp\nf.pl li
+ne 15
1/2
1/2

    [download]

    If you change all the ref $l's to __PACKAGE__ (As I did to create Number::FractionP) you get the expected results: 

    use Number::FractionP;
package Number::FractionP::Foo;
use base qw/Number::FractionP/;
1;
package Number::FractionP::Bar;
use base qw/Number::FractionP/;
1;

my $n=Number::FractionP->new(1,4);
my $f=Number::FractionP::Foo->new(1,4);
my $b=Number::FractionP::Bar->new(1,4);

print $n+$f,$/;
print $n+$b,$/;
print $f+$n,$/;
print $b+$n,$/;
print $f+$b,$/;
print $b+$f,$/;

__END__
1/2
1/2
1/2
1/2
1/2
1/2

    [download]

    So I'd say that ugliness has to take back seat to correctness. Pity.

    :-)


    ---
    demerphq

    <Elian> And I do take a kind of perverse pleasure in having an OO assembly language...
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Re^3: if (UNIVERSAL::isa($r, ref $l))
by adrianh (Chancellor) on Jul 24, 2003 at 10:17 UTC
    I really don't see what advantage __PACKAGE__ has over a hardcoded class name except that it's Pythonesquely uglier.

    I prefer __PACKAGE__ (or CLASS) because I like to say the class name once and only once in the module source (you should know why that's a good motto to live by :-).

    That way I don't have to worry about grepping the module source if I change the name of the module.

[reply]

      That way I don't have to worry about grepping the module source if I change the name of the module.

      You don't put the name of the module in the Pod? ;-)


      ---
      demerphq

      <Elian> And I do take a kind of perverse pleasure in having an OO assembly language...
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[d/l]

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