On Jan 12, 2011 12:10 PM, "Uri Guttman" <u...@stemsystems.com> wrote:
>
> >>>>> "R" == Ruud <rvtol+use...@isolution.nl<rvtol%2buse...@isolution.nl>>
writes:
>
> R> On 2011-01-11 11:44, Uri Guttman wrote:
> >> these are equivilent:
> >>
> >> my @out = grep /foo/, @in ;
> >> my @out = map { /foo/ ? $_ : () } @in ;
>
> R> Indeed equivalent. There is a difference though
> R> in what comes out of map and grep:
>
> R> perl -wle'
> R> my @in = 1 .. 4;
> R> print "@in";
>
> R> ++$_ for map { $_ % 2 ? $_ : () } @in; # copies
> R> print "@in";
>
> R> ++$_ for grep { $_ % 2 } @in; # aliases
> R> print "@in";
> R> '
>
> R> 1 2 3 4
> R> 1 2 3 4
> R> 2 2 4 4
>
Ok, why would that not through an error about directly modifying $_ or is it
only that $_ =~ s/something/me isn't allowed?
What does that 'for' do outside of map/grep?
