in reply to Re: Re: Re: my $var; vs. use constant VAR = '';
in thread my $var = ''; vs. use constant VAR => '';
Interestingly, if you throw a literal value in the mix, as done below, you will find that the literal is even usually a hair slower than a my variable. I'd be very curious to know why that is:
#!/usr/bin/perl -w use strict; use vars qw(*const_alias $const_local); use Benchmark qw(cmpthese); local *const_alias = \100; my $const_ref = \100; local $const_local = 100; my $const_my = 100; sub CONST_SUB () { 100 }; use constant CONST_MOD => 100; print "mod[".CONST_MOD."]\nsub[".CONST_SUB."]\n" ."my[$const_my]\nlocal[$const_local]\n" ."ref[$$const_ref]\nalias[$const_alias]\n"; # run iteratively within the sub to get a less skewed # result - that's my theory anyway :-) my $iter = 500; my $t; cmpthese (-5, { CMod => sub { $t = CONST_MOD for 1..$iter }, CSub => sub { $t = CONST_SUB for 1..$iter }, CMy => sub { $t = $const_my for 1..$iter }, CLocal => sub { $t = $const_local for 1..$iter }, CRef => sub { $t = $$const_ref for 1..$iter }, CAlias => sub { $t = $const_alias for 1..$iter }, CLit => sub { $t = 100 for 1..$iter }, }); ### RESULTS (repeatable this time :) ### Rate CRef CAlias CLocal CSub CLit CMod CMy CRef 3735/s -- -9% -9% -10% -11% -11% -13% CAlias 4088/s 9% -- -0% -2% -3% -3% -5% CLocal 4088/s 9% 0% -- -2% -3% -3% -5% CSub 4172/s 12% 2% 2% -- -1% -1% -3% CLit 4208/s 13% 3% 3% 1% -- -0% -2% CMod 4210/s 13% 3% 3% 1% 0% -- -2% CMy 4293/s 15% 5% 5% 3% 2% 2% --
MeowChow s aamecha.s a..a\u$&owag.print
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Re: Re(4): my $var; vs. use constant VAR = '';
by Rhandom (Curate) on Apr 27, 2001 at 03:33 UTC |
In Section
Seekers of Perl Wisdom