foreach is dead?
dangit... I loved that.
and, java 5 just put in a for loop construct that is very similar to the
foreach.
jen
On Thursday, April 19, 2007, at 08:08AM, "Chas Owens" <[EMAIL PROTECTED]> wrote:
>On 4/19/07, Jenda Krynicky <[EMAIL PROTECTED]> wrote:
>> From: "Chas Owens" <[EMAIL PROTECTED]>
>snip
>> > foreach is dead, long live for.
>>
>> William is dead, long live Bill?
>>
>> foreach and for are two names for the same thing and just as you can
>> call someone both William and Bill you can use foreach and for
>> interchangeably.
>>
>> foreach(my $i = 0; $i < $whatever; $i++)
>> for(my $i = 0; $i < $whatever; $i++)
>>
>> for my $x (@array)
>> foreach my $x (@array)
>>
>> for (@array)
>> foreach (@array)
>>
>> No difference to the computer. Use whichever reads best!
>
>Yes, foreach was aliased to for for backwards compatibility, but, like
>telnet and rsh, it should not be used in new code.
>
>>
>> I would myself use "for" for the C-style loops
>
>And this is why. As long as people think "well, I have foreach which
>is for iterating and for which is for C-style loops" they will
>continue to write C-style loops. C-style loops are bad. They are
>there for backwards compatibility. I can't think of a single for loop
>that isn't better written as a range based for loop or while loop. For
>instance
>
>standard range based loop
>for (my $i = 0; $i < 10; $i++) {}
>for my $i (0 .. 9) {}
>
>often $i winds up being used as an index which just makes me cringe.
>
>The infinite loop
>for (;;) {}
>while (1) {}
>
>The reason C programmers give for using for (;;) is that it generates
>less overhead on their platform, but, at least with my tests*,
>while(1) is more efficient in Perl.
>
>Weirder stuff that you only tend to see people coming from a C background do
>for (my $node = $head; $node = $node; $node->next) {}
>my $node = $head;
>while ($node = $node->next) {}
>
>But in Perl it is rarely necessary to do this sort of loop since most
>functions return a list that can be iterated over using for:
>
>for my $node ($head->nodes) {}
>
>> and if I use the for loop as a way to create an alias
>
>And that is a perfectly idiomatic usage; at least until given is added
>to the language (in 5.10 from what I hear).
>
>* benchmark
> Rate bare for while
>bare 6754/s -- -17% -31%
>for 8179/s 21% -- -17%
>while 9823/s 45% 20% --
>
>#!/usr/bin/perl
>
>use strict;
>use warnings;
>use Benchmark;
>
>
>my %subs = (
> for => sub { my $i; for (;;) { last if $i++ > 1_000 } },
> while => sub { my $i; while (1) { last if $i++ > 1_000 } },
> bare => sub { my $i; { last if $i++ > 1_000; redo } },
>);
>
>Benchmark::cmpthese(-10, \%subs);
>
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>
>
>
>
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