Re: Using Scalar::Util

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Perrin Harkins wrote:

> Drew Taylor wrote:
> 
>> How does this relate to Class::DBI? There are LOTS of checks in method 
>> calls to make sure it is called either as an instance or class method. 
>> They all use something like
>>
>> sub foo {
>>   my $self = shift;
>>   # only called as instance method
>>   return unless ref $self;
>> }
>>
>> I propose that C::DBI should use blessed() instead since it's a better 
>> check.
> 
> 
> You can check this pretty easilly without Scalar::Util by doing the Can 
> can:
> 
> return unless UNIVERSAL::can($self, 'can')
> 
> That's how Template Toolkit does it.  More complete than ref(), but also 
> slower.

Just for curiosity, I benchmarked the 3 methods:

Perl 5.8.3 on FreeBSD 4.8-STABLE (pair.com) running on a Pentium 4 1800 
MHz, 1024MB RAM.

script:
=======

#!/usr/bin/perl -w
use strict;
use Benchmark qw(:all);
use Scalar::Util qw(blessed);

my $count = 500000;
my $tests = {ref    =>sub {my $self = bless {}, 'Foo'; ref $self; },
              blessed=>sub {my $self = bless {}, 'Foo'; blessed $self; },
              univ   =>sub {my $self = bless {}, 'Foo'; 
UNIVERSAL::can($self, 'can') },
          };
cmpthese($count, $tests);
timethese($count, $tests);

Results:
========
             Rate    univ blessed     ref
univ    361582/s      --    -16%    -27%
blessed 429530/s     19%      --    -13%
ref     492308/s     36%     15%      --
Benchmark: timing 500000 iterations of blessed, ref, univ...
    blessed:  1 wallclock secs ( 1.17 usr +  0.00 sys =  1.17 CPU) @ 
426666.67/s (n=500000)
        ref:  2 wallclock secs ( 1.04 usr +  0.00 sys =  1.04 CPU) @ 
481203.01/s (n=500000)
       univ:  0 wallclock secs ( 1.34 usr +  0.00 sys =  1.34 CPU) @ 
372093.02/s (n=500000)

So ref() is fastest (no surprise), but blessed is only 13% slower. 
Anyway food for thought.

Drew
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