[Templates] Array ref returned from plugin can't be unshifted?

[Jim Spath]

The value of first is not an array reference.  It is a code reference, 
which means unshift won't work on it.

Bill Moseley wrote:
> Hey, can anyone repeat this or explain what obvious mistake I made?
> 
> Thanks,
> 
> On Tue, Jun 26, 2007 at 11:51:07AM -0700, Bill Moseley wrote:
>> I've got a plugin that returns an array ref.  Not sure what was in my
>> coffee this morning, but when I then try to unshift another element
>> onto that array ref nothing happens.
>>
>> But if I copy the value return from the plugin and then unshift than
>> then that works fine.
>>
>>
>>
>> $ cat arrayref.pl
>>
>>     use strict;
>>     use warnings;
>>     use Template;
>>
>>
>>     Template->new->process( \*DATA ) or die;
>>
>>     __END__
>>
>>     In template
>>     [%
>>         USE Dumper;
>>         USE first = Arrayref;
>>
>>         Dumper.dump( first );
>>
>>         first.unshift( [ { foo => 'bar' } ] );
>>
>>         "note no change\n";
>>         Dumper.dump( first );
>>
>>         "no copy and change\n";
>>
>>         x = first;
>>
>>         x.unshift( [ { foo => 'bar' } ] );
>>
>>         first = x;
>>
>>         Dumper.dump( first );
>>     %]
>>
>>
>> $ perl arrayref.pl
>>
>> In template
>> $VAR1 = [                       <<<< array ref returned from plugin
>>           [
>>             {
>>               'one' => 1,
>>               'two' => 2
>>             },
>>             {
>>               'three' => 2,
>>               'four' => 4
>>             }
>>           ],
>>           [
>>             {
>>               'xone' => 1,
>>               'xtwo' => 2
>>             },
>>             {
>>               'xthree' => 2,
>>               'xfour' => 4
>>             }
>>           ]
>>         ];
>>
>>
>> note no change
>> $VAR1 = [                       <<<< first.unshift
>>           [
>>             {
>>               'one' => 1,
>>               'two' => 2
>>             },
>>             {
>>               'three' => 2,
>>               'four' => 4
>>             }
>>           ],
>>           [
>>             {
>>               'xone' => 1,
>>               'xtwo' => 2
>>             },
>>             {
>>               'xthree' => 2,
>>               'xfour' => 4
>>             }
>>           ]
>>         ];
>>
>> no copy and change              <<<< copy and push
>> $VAR1 = [
>>           [
>>             {
>>               'foo' => 'bar'    <<< works!
>>             }
>>           ],
>>           [
>>             {
>>               'one' => 1,
>>               'two' => 2
>>             },
>>             {
>>               'three' => 2,
>>               'four' => 4
>>             }
>>           ],
>>           [
>>             {
>>               'xone' => 1,
>>               'xtwo' => 2
>>             },
>>             {
>>               'xthree' => 2,
>>               'xfour' => 4
>>             }
>>           ]
>>         ];
>>
>>
>>
>>
>> $ cat Template/Plugin/Arrayref.pm 
>> package Template::Plugin::Arrayref;
>> use strict;
>> use warnings;
>> use Data::Dumper;
>>
>> use base 'Template::Plugin';
>>
>> sub new {
>>
>>
>>     return sub {
>>
>>         return [
>>             [
>>                 { one => 1, two => 2, },
>>                 { three => 2, four => 4, },
>>             ],
>>             [
>>                 { xone => 1, xtwo => 2, },
>>                 { xthree => 2, xfour => 4, },
>>             ],
>>         ];
>>     }
>> }
>> 1;