2010/1/19 Hans Dieter Pearcey <h...@pobox.com>:
> Excerpts from Dermot's message of Tue Jan 19 08:28:55 -0500 2010:
>> 2010/1/19 Hans Dieter Pearcey <h...@pobox.com>:
>> > subtype 'Whatever', as enum([ qw(foo bar baz) ]), ...;
> ^^^^^^^^^^^^^^^^^^^^^^^^^
>
>> So the answer is use 'as'.
>
> Yes, that is *part* of the answer. Look at the rest of the example.
>
>> subtype 'IndexType'
>> => as enum( $_, qw[foo bar baz]),
>
> This only works accidentally.
>
> You are taking whatever is in $_ (maybe undef, maybe .. who knows) and
> declaring an enum with that name. This form of enum() happens to also return
> that type name, but that's an implementation detail and not documented, so you
> shouldn't depend on it.
>
> If you're unlucky, some day $_ will contain "Int" and all your integer
> attributes will suddenly start throwing error messages about how they don't
> match "foo", "bar", or "baz".
my $indexer = MyApp::Local::Indexer->new(index_type=>'foobarquin);
I thought $_ was the value passed by the constructor arguments. In
this case, $_ ='foobarquin' and it would been used to cmp against the
strings in the array.
> Did you read the docs for enum() in Moose::Util::TypeConstraints?
I did but I'm struggling. I can see from the 2nd (arrayref) enum
reference that the form: enum ($name, \...@values) returns an named enum.
Which is like the example "enum 'RGBColors' => qw(red green blue);" So
my enum($_, \...@array) would have created a subtype who's name was
whatever was in $_. Ok, if that's true, that's not what I intended.
For me the issue was turning this
enum 'IndexType' => qw(foo bar baz);
has 'index_type' => (isa => 'IndexType');
into
subtype 'IndexType',
=> as enum( [qw(foo bar baz)] ),
=> message {'Wrong type'};
has 'index_type' => (isa => 'IndexType');
now the above works. Is this a correct implementation? Could this have
been done with a named enum? Would it make sense to create a named
enum type inside a subtype?
The docs say that you can construct constraints with
subtype 'Name' => as 'Parent' => ....
Are these 'Parents' objects the class_type, duck_type and enum as well
as other Classes you might want to harness?
Thanks again,
Dp.
Thanks.
Dp.
