On Mon, Nov 24, 2008 at 08:15, Mr. Shawn H. Corey <[EMAIL PROTECTED]> wrote:
> On Mon, 2008-11-24 at 18:41 +0530, suresh kumar wrote:
>> Thanks for the response.
>>
>> but is there anyother way to do this?
>>
>
> You just got three answer all essentially the same. What's wrong with
> them?
snip
Well, because you are returning 1 or 0 you could use the bitwise and
operator (&) since it doesn't use short circuit logic, but that would
not be very maintainable (3 & 1 is true, but 2 & 1 is false). I would
suggest using the example many other people gave you over this.
sub a {
print "i am a\n";
return 0;
}
sub b {
print "i am b\n";
return 1;
}
if (a() & b()) {
print "yes\n";
} else {
print "no\n";
}
Hmm, now that I think about it, it might be safer to say
sub a {
print "i am a\n";
return 0;
}
sub b {
print "i am b\n";
return 1;
}
if (!!a() & !!b()) {
print "yes\n";
} else {
print "no\n";
}
This at least tests the truthiness of a() and b(), but it is still not
a nice thing to do to someone who reads your code later. There isn't
even a performance gain (logical is faster than bitwise, who knew).
bitwise 0
broken 0
logical 0
Rate bitwise broken logical
bitwise 4858803/s -- -22% -43%
broken 6199351/s 28% -- -27%
logical 8498074/s 75% 37% --
bitwise 0
broken 0
logical 0
Rate bitwise broken logical
bitwise 5687007/s -- -6% -33%
broken 6053143/s 6% -- -29%
logical 8495407/s 49% 40% --
bitwise 1
broken 1
logical 1
Rate bitwise broken logical
bitwise 4626070/s -- -4% -35%
broken 4828968/s 4% -- -32%
logical 7126245/s 54% 48% --
bitwise 1
broken 0
logical 2
Rate bitwise broken logical
bitwise 4077795/s -- -34% -46%
broken 6175150/s 51% -- -18%
logical 7502893/s 84% 22% --
#!/usr/bin/perl
use strict;
use warnings;
use List::Util;
use Benchmark;
my %subs = (
broken => sub { my $bool = $a & $b; return $bool },
bitwise => sub { my $bool = !!$a & !!$b; return $bool },
logical => sub { my $bool = $a && $b; return $bool },
);
$a = 0;
$b = 0;
for my $sub (sort keys %subs) {
print "$sub ", $subs{$sub}->(), "\n";
}
Benchmark::cmpthese(-1, \%subs);
print "\n";
$a = 0;
$b = 1;
for my $sub (sort keys %subs) {
print "$sub ", $subs{$sub}->(), "\n";
}
Benchmark::cmpthese(-1, \%subs);
print "\n";
$a = 1;
$b = 1;
for my $sub (sort keys %subs) {
print "$sub ", $subs{$sub}->(), "\n";
}
Benchmark::cmpthese(-1, \%subs);
print "\n";
$a = 1;
$b = 2;
for my $sub (sort keys %subs) {
print "$sub ", $subs{$sub}->(), "\n";
}
Benchmark::cmpthese(-1, \%subs);
print "\n";
--
Chas. Owens
wonkden.net
The most important skill a programmer can have is the ability to read.
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