Re: [FWP] thoughts on while(defined(EXP warnings

[Michael G Schwern <schwern@pobox.com>]

On Mon, Mar 13, 2000 at 08:40:29PM +0000, David L. Nicol wrote:
> "defined" is implemented as a function call in these
> cases, and profiling indicates that a performance hit is taken,
> contrary to the performance improvement  I had hoped for

I don't see any performance drop when reading in a fairly large file:

#!/usr/bin/perl -w

use Benchmark;

# Might be /usr/dict/words
$FILE = "/usr/share/dict/words";

timethese(shift || -3, 
          {
           "defined" => sub {
               open(FILE, $FILE) or die $!;
               while(defined($line = <FILE>)) { 1 }
           },
           "no defined" => sub {
               open(FILE, $FILE) or die $!;
               while($line = <FILE>) { 1 }
           },
          }
         );

$ perl -w src/bench/defined_vs_not -10
Benchmark: running defined, no defined, each for at least 10 CPU seconds...
   defined: 13 wallclock secs (12.86 usr +  0.32 sys = 13.18 CPU) @  5.84/s (n=77)
no defined: 13 wallclock secs (12.86 usr +  0.22 sys = 13.08 CPU) @  5.89/s (n=77)

(Similar results under 5.6 as under 5.005_03, similar results with a
small file)


-- 

Michael G Schwern      http://www.pobox.com/~schwern/	   schwern@pobox.com
Sometimes these hairstyles are exaggerated beyond the laws of physics
	   - Unknown narrator speaking about Anime

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