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Showing posts from November, 2010

More Perl 5 - Comparing "split range" vs "test in loop"

Although the difference I found between the split range and the test within loop implementations were small, it seems to me it's wrong.

So I boiled the test down to a bar minimum. I created a benchmark test consisting of nothing but the loop. I had to do something within the loop, so I stored the number in a variable.

test8 => sub { for ( 0..8 ) {
next if $_ == 8;
my $j = $_;
} },
range0 => sub { for ( 0..-1,1..8) {
my $j = $_;
} },

As the names and the code suggest, I actually had 9 test and 9 range instances, for each value in 0..8. While there was a little variation within the sets, the difference between sets was significant! Using a split range was 60% faster than testing within the loop. The test achieved 376923 .. 390809 iterations per second, compared to 596918 .. 606710 for the split range, when tested for 10 seconds per version. Testing just test4 vs range4 for a minute gave similar re…