I did not suspect that the subroutine made a copy of the memory address

It doesn't. You do, with the my($data) = @_; snippet. If you directly manipulate the argument, it works as you expect:

sub clear_it {
    $_[0] = [];
}

[download]

Because you're then working on the original reference, not on the copy you made.

In reply to Re^3: Pass array, then clear by Crackers2
in thread Pass array, then clear by Anonymous Monk

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