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]

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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?

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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