Re: [Moose eats exports] The Moose seems extra hungry today?

Benh,

An imported sub is not a method, Roles only deal with methods.

So in the first test the looks_like_number is only available as a  
function in the role package itself and not in My::Class since the  
role composition sees that it is imported from Scalar::Util and not  
defined in the role itself.

In the second one, the import method is created by Exporter and  
therefore *should* be composed into My::Class2 however I suspect that  
&import would, if you were to introspect it have a package of  
"Exporter" and a name of "__ANON__" and so Moose role composition  
would ignore it. Also, this wouldn't work as expected anyway because  
with 'My::Role' does not call ->import it only loads the role package  
with require.

In the 3rd example with extends, you are not inheriting the exports  
so you cannot call it as looks_like_number and have Perl's sub  
dispatcher find it. However you could call it as a method $self- 
 >look_like_number and have Perls method dispatcher find it. However  
this is not very useful since $self will never be a number and will  
be the first arg passed to look_like_number.

In the 4th example, your My::Ext2 class will actually inherit the  
import method, so if you were to do:

   package Foo;
   use My::Ext2;

Then looks_like_number would actually get imported into Foo. However,  
as with roles, when you do extends 'My::Base' it will not call  
My::Base->import and so never import the looks_like_number function.

As I mentioned on IRC, apparently Spiffy used to do this, and Ingy  
mentioned at YAPC that he would like to write a MooseX:: module to do  
the same. It would be fairly simple and would take some work on your  
part to determine what is imported and what is not, but all the tools  
are there for you (Class::MOP::Package symbol table introspection  
will help a lot, along with the Class::MOP::get_code_info util sub).

- Stevan

On Jun 23, 2008, at 7:37 PM, benh wrote:

> So I'm sure that this is due to my lack of understating on how Objects
> are built behind the fur but it seems that if I use something in a
> role that I should use it in the caller, same with a base class with a
> sub class? Have I completely missed something obvious?
>
> I've written up a test to illustrate the point. Sadly all the tests
> pass (throws_ok) ?
>
> http://develonizer.com/svn/misc/role_use.t
>
>
> -- 
> benh~