Returning reference to an array

[Andrew Fleet]

Hi,
I'm looking at returning a reference to an array I create within a
subroutine.

I could do this...

sub foo {
my @theArray;

<snip>

return \@theArray;
}

This works however I'm concerned I'm returning a reference to stack data. I
heard if I used 'local' rather than 'my' the array will always exist (it's
global), but using 'my' I'm creating a temporary stack based
array that will then be cleaned up when the subroutine returns, hence my
reference will be invalid.

So...my or local?

Thanks

Andy

[Eric J. Roode]

Re: Returning reference to an array

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"Andrew Fleet" <areconsulting@ earthlink.net> wrote in
news:Yyimb.734$ Px2.385@newsrea d4.news.pas.ear thlink.net:
[color=blue]
> I'm looking at returning a reference to an array I create within a
> subroutine.
>
> I could do this...
>
> sub foo {
> my @theArray;
>
> <snip>
>
> return \@theArray;
> }
>
> This works however I'm concerned I'm returning a reference to stack
> data. I heard if I used 'local' rather than 'my' the array will always
> exist (it's global), but using 'my' I'm creating a temporary stack
> based array that will then be cleaned up when the subroutine returns,
> hence my reference will be invalid.
>
> So...my or local?[/color]

Use 'my'. You heard wrong. Perl data structures are cleaned up when
there are no more remaining references to them. When you declare
@theArray with 'my', a new data structure is created. When you return
\@theArray and presumably store that return value into a variable, there
is still an extant reference to the array. When all references to the
array go out of scope or are reassigned, then the array will be garbage-
collected.

For your future reference, comp.lang.perl is a defunct newsgroup. Please
post general perl questions to comp.lang.perl. misc; you'll get a better
response there.

- --
Eric
$_ = reverse sort $ /. r , qw p ekca lre uJ reh
ts p , map $ _. $ " , qw e p h tona e and print

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