Re: Re: Benchmarking File Retrevial

I'm getting my Benchmark syntax from Programming Perl. Here's the example in the book:

use Benchmark qw/countit cmpthese/;
sub run($) { countit(5, @_) }
for $size (2, 200, 20_000) {
    $s = "." x $len;
    print "\nDATASIZE = $size\n";
    cmpthese {
        chop2   => run q{
            $t = $s; chop $t; chop $t;
        },
        subs    => run q{
            ($t = $s) =~ s/..\Z//s;
        },
        lsubstr => run q{
             $t = $s; substr($t, -2) = '';
        },
        rsubstr => run q{
             $t = substr($s, 0, length($s)-2);
        },

    };
}
[download]

Reinitializing @hitwords is a good idea. I'll try it. Also, I thought the only difference between while($word = <WORDS>){ and while(<WORDS>){ was that in the latter, the line was stored in !_. I haven't been able to find any documentation to the contrary, although I'd believe there might be a difference.

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Re: Re: Re: Benchmarking File Retrevial by chromatic (Archbishop) on Dec 15, 2002 at 23:51 UTC
Use B::Deparse. I think it may be documented in perlopen, but the second construct adds the `defined` operator. `$ perl -MO=Deparse while (<STDIN>) { print; }` [download] produces: `while (defined($_ = <STDIN>)) { print $_; } - syntax OK` [download]	[reply] [d/l] [select]
Re: Re: Re: Benchmarking File Retrevial by demerphq (Chancellor) on Dec 16, 2002 at 00:06 UTC
Well unless theres a version issue going on here then I would write that benchamrk like this `use Benchmark 'cmpthese'; for $size (2, 200, 20_000) { $s = "." x $len; print "\nDATASIZE = $size\n"; cmpthese -5,{ chop2 => '$t = $s; chop $t; chop $t;', subs => '($t = $s) =~ s/..\Z//s;', lsubstr => '$t = $s; substr($t, -2) = "";', rsubstr => '$t = substr($s, 0, length($s)-2);', }; }` [download] There are a few more ways, but this is a direct but less verbose copy of what you posted. The -5 argument indicates that the benchmarking for each item should take at minimum 5 seconds. (It may take longer) If you used a positive argument then it does that many runs of the given code. It will warn if you dont use enough iterations for it to get a "reasonable" sample. Please consult the Benchmark documentation as I suspect the interface has moved on since the edition of Programming Perl that you are using. I say this because your code does work, but it looks like Benchmark has been updated to do that idiom automatically. cheers --- demerphq my friends call me, usually because I'm late....	[reply] [d/l]