Re: Predicate

Peter,

The doc never got updated, I have fixed it in SVN as:

"The next attribute option is new, though: the C<predicate> option.  
This option creates a method which can be used to check whether a  
given slot (in this case C<parent>) has been initialized"

- Stevan

On Apr 4, 2008, at 4:25 PM, Piotr Jackowski wrote:
> Hi Developers,
>
> Here http://search.cpan.org/~stevan/Moose/lib/Moose/Cookbook/ 
> Recipe3.pod I
> can read:
> "The next attribute option is new, though: the predicate option.  
> This option
> creates a method which can be used to check whether a given slot  
> (in this
> case parent) contains a defined value. In this case it will create  
> a method
> called has_parent. Quite simple, and quite handy too."
>
> Truly said predicate checks if value was set or not.
> When I will set attribute with 'undef' actually predicate will say  
> 'true'.
> Moose version 0.40.
>
> Please see this simple test:
>
> #!/perl
>
> use strict;
> use warnings;
>
> use Carp;
> use Data::Dumper;
>
> use Test::More qw(no_plan);
> use Test::Exception;
>
> package TestPredicate;
> use Moose 0.40;
>
>
> has 'item' => ( is => 'ro',
>                 isa => 'Str|Undef',
>                 predicate => 'has_item');
>
> no Moose;
>
> package main;
>
>
> my $obj1 = TestPredicate->new();
> ok( !$obj1->has_item, "I don't have value, because I didn't give  
> anything");
>
>
> my $obj2 = TestPredicate->new( item => undef );
> ok( !$obj2->has_item, "I shouldn't have item, but I set undef");
>
>
>
> I miss something or there is a bug ?
>
>
> Thanks!
> Peter