>>>>> "PM" == Paul Makepeace <paul.makepe...@realprogrammers.com> writes:
PM> On Tue, May 31, 2011 at 22:41, Nick Patch <n...@atemoya.net> wrote:
>> use Benchmark qw( cmpthese );
>>
>> cmpthese(-2, {
>> assign => sub { my $x = 'bar'; $x = "foo/$x" },
>> substr => sub { my $x = 'bar'; substr $x, 0, 0, 'foo/' },
>> lvalue => sub { my $x = 'bar'; substr($x, 0, 0) = 'foo/' },
>> });
PM> Oddly(?) join() is 20% faster than assignment:
PM> ...
PM> join => sub { my $x = 'bar'; $x = join('/', 'foo', 'bar') },
PM> oooscf => sub { my $x = 'bar'; $x = File::Spec->catfile($x, 'bar') },
PM> fnoscf => sub { my $x = 'bar'; $x = catfile($x, 'bar') },
PM> Rate fnoscf oooscf lvalue assign join substr
PM> fnoscf 146161/s -- -6% -94% -95% -96% -97%
PM> oooscf 155614/s 6% -- -93% -95% -96% -97%
PM> lvalue 2307768/s 1479% 1383% -- -28% -41% -59%
PM> assign 3190698/s 2083% 1950% 38% -- -18% -43%
PM> join 3912592/s 2577% 2414% 70% 23% -- -30%
PM> substr 5609155/s 3738% 3505% 143% 76% 43% --
my view would be join has a very fast string build up. it could
preallocate the length of the string so no extra copying is
needed. assign is really plain interpolation but assigning back to a var
used in it. i wonder if assigning to another var would speed it up a
bit. perl may not be smart enough in that case to optimize but join can
do that. same for 4 arg substr.
uri
--
Uri Guttman ------ u...@stemsystems.com -------- http://www.sysarch.com --
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