Perl does not employ a copy-on-write mechanism. As such, assigning a one array to another (as in the second example) involves copying the elements, not just copying a reference to the elements.

In the first example, you're not even assigning an array to an array. You're getting a list of the elements in the array, then you're assigning that list to another array. You might end up copying each element twice! I know there's at least one optimisation in place, but there's no escaping copying each element at least once for the reason I gave above.

In reply to Re: returning large arrays from functions by ikegami
in thread returning large arrays from functions by perl5ever

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