Using grep on undefined array
Matt Lawrence
matt.lawrence at virgin.net
Wed Aug 14 08:10:26 BST 2013
On 14/08/2013 00:09, Andrew Beverley wrote:
> Hi,
>
> Could someone please explain to me why the following outputs an empty
> string rather than "*"?
>
> get();
> sub get($)
> { my $fields = shift;
> my @fields = grep $_ ne 'domain', @$fields;
> my $select_fields = $fields ? join(',', map { 'users.' . $_ } @fields) : '*';
> print "$select_fields\n";
> }
>
> I would have expected $fields to remain undefined, but it seems to be
> turning into an empty array during the grep.
>
Search "autovivification" to get an explanation of why this happens.
Also, what would you expect the result of get(['domain']) to be?
Matt
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