[ruby-core:52746] Re: [ruby-trunk - Feature #7914] Case for local class methods

Thomas Sawyer, you are the language troll, IMHO.

(But, maybe I'm too)

Everyone else, excuse me for not being polite.
23.02.2013 12:17 ミマフリレマラチヤナフリ "trans (Thomas Sawyer)" <[e-mail]>
ホチミノモチフ:

>
> Issue #7914 has been updated by trans (Thomas Sawyer).
>
>
> @rosenfeld Maybe I approached this backwards. I just wanted to show one
> possible use case for supporting local vs. non-local class methods. Your
> in-method conditional solution works for this specific case, true. But how
> well does it translate to other cases? For instance, it would not work with
> anonymous classes. called_by_super is an interesting notion, but after some
> thought it feels like a make shift approach that only address part of the
> wider issue. The module non-local side of this is important too. And its
> use case is much more obvious --everywhere the included/ClassMethods hack
> is used.
>
>
>
>
> ----------------------------------------
> Feature #7914: Case for local class methods
> https://bugs.ruby-lang.org/issues/7914#change-36827
>
> Author: trans (Thomas Sawyer)
> Status: Open
> Priority: Normal
> Assignee: matz (Yukihiro Matsumoto)
> Category: core
> Target version: next minor
>
>
> =begin
> Here is a use case for local class methods.
>
> Say we wish to give certain classes and all subclasses a special name.
>
>   class X
>     def self.special_name
>       "special:#{name}"
>     end
>   end
>   class Y < X; end
>   class Z < Y; end
>
>   Z.special_name  #=> "special:Z"
>
> But what if Y has a unique special name?
>
>   class Y < X
>     def special_name
>       'unique:Y'
>     end
>   end
>
> Problem that arises:
>
>     Z.special_name  #=> "unique:Y"  # wrong!
>
> Currently, to solve this would require creating an additional method, e.g.
> `unique_name` and redefine `special_name` to first look for unique_name
> then fallback to default special name if non-found. It works, but adds
> additional complexity to API.
>
> Nicer solution would be local class methods.
>
>     class Y < X
>       def special_name
>         'unique:Y'
>       end
>       local :special_name
>     end
>
>     Y.special_name  #=> "unique:Y"
>     Z.special_name  #=> "special:Z"
>
> The idea being that local class methods are skipped in super/lookup chain.
>
> This idea is not without precedence. Module class methods can be thought
> of as being local. So this idea has other side of the notion, that modules
> could have class methods that are not skipped over in the super/lookup
> chain. In that case we would need a term that means opposite of local, so
> I'll use `nonlocal`:
>
>     module M
>       def self.q; "q"; end
>       nonlocal :q
>     end
>
>     class X
>       include M
>     end
>
>     X.q  #=> "q"
>
> =end
>
>
>
> --
> http://bugs.ruby-lang.org/
>
>