Re^7: Removing AUTOLOAD from CGI.pm (closure vs eval)

[LanX]

> I'm sure compilation speed shouldn't matter when generating closures. (I will add a benchmark later this day)

Here a simplified example which showed that installing subs with closures¹ is 5 times faster than eval.

That's less dramatic than I thought, but eval performance also heavily depends on the length of code.

So adding 10 no-ops already made eval 10 times slower while closure didn't change.

use strict;
use warnings;
use Time::HiRes qw/time/;


BEGIN {
    $\="\n";
    my $count=1000;
    sub noop { };
    
    my $start=time;
    sub tag_gen {
        my ($tag)=@_;
        sub {
            noop("Ipse Lorum");
            noop("Ipse Lorum");
            noop("Ipse Lorum");
            noop("Ipse Lorum");
            noop("Ipse Lorum");
            noop("Ipse Lorum");
            noop("Ipse Lorum");
            noop("Ipse Lorum");
            noop("Ipse Lorum");
            noop("Ipse Lorum");
            "<$tag>",@_,"</$tag>";
        }
    }
    {
        no strict 'refs';
        for my $x (1..$count) {
            
            my $tag="h$x";
            *{$tag}=tag_gen($tag);
        }
    }
    print "Closure: ",time-$start;

    
    $start = time;
    for my $x (1..$count) {
        my $tag="H$x";
        eval sprintf <<'__CODE__', $tag;
        sub %1$s {
            noop("Ipse Lorum");
            noop("Ipse Lorum");
            noop("Ipse Lorum");
            noop("Ipse Lorum");
            noop("Ipse Lorum");
            noop("Ipse Lorum");
            noop("Ipse Lorum");
            noop("Ipse Lorum");
            noop("Ipse Lorum");
            noop("Ipse Lorum");

            "<%1$s>",@_,"</%1$s>";
        }
__CODE__
    }
    print "Eval: ",time-$start;
}





print h1 h2 "closure";

print H1 H2 "eval";

output:

Closure: 0.0279860496520996
Eval: 0.343567132949829
<h1><h2>closure</h2></h1>
<H1><H2>eval</H2></H1>

One has to keep in mind that 15-20 years ago machines were factor 1000 slower, i.e. auto loading was relevant.

update

fixed bug with no-ops.

¹) currying to be precise