hi all,
i just saw a post on the perl beginner's list and it was prepending a
dir to a filename with the usual $x = "$dir/$x. i replied that 4 arg
substr is usually faster. i wanted to make sure so i ran a simple
benchmark on this. the code and results are below. it is faster because
it knows how to directly manipulate a string in the perl guts. the
assign method has to do a full copy of the string and reallocate the var
buffer to do that.
#!/usr/local/bin/perl
use Benchmark qw( cmpthese ) ;
cmpthese ( shift || -2, {
assign => sub { my $x = 'abc' ; $x = "qwerty/$x" },
substr => sub { my $x = 'abc' ; substr( $x, 0, 0, 'qwerty/') },
}
) ;
Rate assign substr
assign 2356409/s -- -47%
substr 4428292/s 88% --
so my question for you all is do you use 4 arg substr? have you ever
seen it before? it is newer than 3 arg substr but it has been in perl
for a good while now. if you have any questions on this function
(actually an option on a function) post them here. i think it should be
used much more often that i see it.
this could be a good ongoing topic. post some other cool features you
think are underused in perl.
uri
--
Uri Guttman ------ [email protected] -------- http://www.sysarch.com --
----- Perl Code Review , Architecture, Development, Training, Support ------
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