I think the issue is that you aren’t passing the array to the subroutine,
you’re passing a new flattened list of aliases to the elements of the array.
If you modify a parameter (`$_[3] = ‘xyzzy’;), it changes at the top level,
but that’s because you’re modifying the aliases parameter.
From `perlsub`:
> The array @_ is a local array, but its elements are aliases for the
> actual scalar parameters.
So, you create an array “@list”, which has a bunch of elements. You pass
that array to the killer functions, but Perl flattens the array, and
instead of passing “@list”, it passes @_ = ( $list[0], $list[1], $list[2],
$list[3], …). When you modify @_, you’re not modifying @list, just @_. If
you change $_[2], you change the aliases item, which changes the value that
$list[2] points to, so you can change it that way, but you can’t change
@list itself.
If you need to modify @list, you need to pass the sub a reference to @list
— `killer(\@list)` — similar to why you had to escape @list to pass it to
`Dumper`. You would then be able to delete an item with
`delete($_[0]->[2])`.
HTH,
Ricky
On Dec 19, 2019, at 3:53 PM, Greg London <em...@greglondon.com> wrote:
> External Email - Use Caution
>
> use Data::Dumper;
>
> sub killer{
> delete($_[2]);
> }
>
> my @list = qw( alpha bravo charlie delta echo fox);
> print Dumper \@list;
> killer(@list);
> print Dumper \@list;
>
>
> I would expect the second Dumper statement to show one less element.
> Greg
>
> _______________________________________________
> Boston-pm mailing list
> Boston-pm@pm.org
> https://mail.pm.org/mailman/listinfo/boston-pm
_______________________________________________
Boston-pm mailing list
Boston-pm@pm.org
https://mail.pm.org/mailman/listinfo/boston-pm
