Re: Problem emulating built-ins like map and grep.

For what it is worth your sub works both ways using Perl 5.8. I tried it using the activestate distribution:

use strict;

sub map2 (&@) {
    use Carp;
    my $code = shift;
    croak 'Odd number of values in list' if @_ & 1;
    map { local ($a, $b) = (shift,shift); $code->() } 1 .. (@_>>1);
}

my @array = ('A'..'J');
print 'PRINTING map2{ print "$a $b"; } @array; =>';

map2{ print "$a $b"; } @array;

print "\n",'PRINTING map2{ print "$a $b"; } qw[A B C D]; =>';

map2{ print "$a $b"; } qw[A B C D E F G H I J];
[download]

resulting in

E:\>228837.pl
PRINTING map2{ print "$a $b"; } @array; =>A BC DE FG HI J
PRINTING map2{ print "$a $b"; } qw[A B C D]; =>A BC DE FG HI J
[download]

and also using Perl 5.8 (built from source on a SCO OSR5.5):

#!/usr/bin/perl -slw

use strict;

sub map2 (&@) {
    use Carp;
    my $code = shift;
    croak 'Odd number of values in list' if @_ & 1;
    map { local ($a, $b) = (shift,shift); $code->() } 1 .. (@_>>1);
}

my @array = ('A'..'J');
print 'PRINTING map2{ print "$a $b"; } @array; =>';

map2{ print "$a $b"; } @array;

print "\n",'PRINTING map2{ print "$a $b"; } qw[A B C D]; =>';

map2{ print "$a $b"; } qw[A B C D E F G H I J];
[download]

resulting in:

{sco}>./228837.pl
PRINTING map2{ print "$a $b"; } @array; =>
A B
C D
E F
G H
I J

PRINTING map2{ print "$a $b"; } qw[A B C D]; =>
A B
C D
E F
G H
I J
[download]

update:I have just tried it on a RH Linux Box and as expected works one way and not the other (Perl 5.6.1).

Hope this helps.

-enlil

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Re: Re: Problem emulating built-ins like map and grep. by BrowserUk (Patriarch) on Jan 21, 2003 at 22:05 UTC
Thanks Enlil. Time to upgrade I guess, but I thought I heard there were problems with the current AS distribution, and my attempts to build perl have ground to a halt so far. Examine what is said, not who speaks. The 7th Rule of perl club is -- pearl clubs are easily damaged. Use a diamond club instead.	[reply]