From: ara.t.howard@...
Date: 2006-06-15T03:09:02+09:00
Subject: Re: Why the lack of mixing-in support for Class methods?

---1400102478-735090016-1150308539=:4620
Content-Type: MULTIPART/MIXED; BOUNDARY="-1400102478-735090016-1150308539=:4620"

  This message is in MIME format.  The first part should be readable text,
  while the remaining parts are likely unreadable without MIME-aware tools.

---1400102478-735090016-1150308539=:4620
Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed

On Thu, 15 Jun 2006, Daniel Schierbeck wrote:

> gwtmp01@mac.com wrote:
>> 
>> On Jun 14, 2006, at 10:30 AM, transfire@gmail.com wrote:
>>> Okay, so I'm wondering, will the annonymous module this creates get a
>>> name of some sort instead of the ususal "#<Module:0xb7ca7e1c>"
>> 
>> I was thinking that the block would just be evaluated in the context of
>> the targeted singleton class as vs. the context of a new anonymous
>> module which is *then* included into the targeted singleton class.
>
> Then inheritance problems will arise --  I think we need to use modules.

can someone point out to me what's wrong with this impl?  it's simple, works
in a recursive way, is self documenting, is already used, and is 34 lines
long.  as far as i can tell it already does every required and it very simple
and robust.


module Mixable
   Mixin = lambda do |this, other|
     cm = this.const_get 'ClassMethods' rescue nil
     im = this.const_get 'InstanceMethods' rescue nil
     other.extend cm if cm
     other.module_eval{
       include im if im
       extend RecursiveMixin
     }
   end
   module RecursiveMixin
     def included other
       Mixin[self, other]
       super
     end
   end
   extend RecursiveMixin
end
class Object
   def mixin other
     sc =
       class << self
         self
       end
     sc.module_eval{ mixin other }
   end
end
class Module
   def mixin other
     other.module_eval{ include Mixable } unless
       Mixable > other
     include other
   end
end



if __FILE__ == $0
#
# example 1 - simple usage
#
   module M
     include Mixable
     module ClassMethods
       def foo() 42 end
     end
   end
   class C
     include M
   end
   p C.foo #=> 42

#
# example 2 - note the how it works recursively
#
   module A
     include Mixable
     module ClassMethods
       def bar() 'forty-two' end
     end
     module InstanceMethods
       def foobar() 42.0 end
     end
   end
   module B
     include A
   end
   class K
     include B # and recurively add ClassMethods from A!
   end
   p K.bar        #=> 'forty=two'
   p K.new.foobar #=> 42.0

#
# example 3 - we needn't both with Mixable if the 'includee' specifies that it
# wants to to a mixin
#
   module M
     module ClassMethods
       def bar() 42.0 end
     end
     def foo() 42 end
   end
   class C
     mixin M
   end
   p C.bar     #=> 42.0
   p C.new.foo #=> 42

#
# and, of course, it works with objects
#
   mixin M
   p foo #=> 42
   class << self
     p bar #=> 42.0
   end

end


-a
-- 
suffering increases your inner strength.  also, the wishing for suffering
makes the suffering disappear.
- h.h. the 14th dali lama
---1400102478-735090016-1150308539=:4620
Content-Type: TEXT/PLAIN; charset=US-ASCII; name=mixable.rb
Content-Transfer-Encoding: BASE64
Content-ID: <Pine.LNX.4.62.0606141208590.4620@harp.ngdc.noaa.gov>
Content-Description: 
Content-Disposition: attachment; filename=mixable.rb

bW9kdWxlIE1peGFibGUNCiAgTWl4aW4gPSBsYW1iZGEgZG8gfHRoaXMsIG90
aGVyfA0KICAgIGNtID0gdGhpcy5jb25zdF9nZXQgJ0NsYXNzTWV0aG9kcycg
cmVzY3VlIG5pbA0KICAgIGltID0gdGhpcy5jb25zdF9nZXQgJ0luc3RhbmNl
TWV0aG9kcycgcmVzY3VlIG5pbA0KICAgIG90aGVyLmV4dGVuZCBjbSBpZiBj
bQ0KICAgIG90aGVyLm1vZHVsZV9ldmFsew0KICAgICAgaW5jbHVkZSBpbSBp
ZiBpbQ0KICAgICAgZXh0ZW5kIFJlY3Vyc2l2ZU1peGluDQogICAgfQ0KICBl
bmQNCiAgbW9kdWxlIFJlY3Vyc2l2ZU1peGluIA0KICAgIGRlZiBpbmNsdWRl
ZCBvdGhlcg0KICAgICAgTWl4aW5bc2VsZiwgb3RoZXJdDQogICAgICBzdXBl
cg0KICAgIGVuZA0KICBlbmQNCiAgZXh0ZW5kIFJlY3Vyc2l2ZU1peGluDQpl
bmQNCmNsYXNzIE9iamVjdA0KICBkZWYgbWl4aW4gb3RoZXINCiAgICBzYyA9
IA0KICAgICAgY2xhc3MgPDwgc2VsZg0KICAgICAgICBzZWxmDQogICAgICBl
bmQNCiAgICBzYy5tb2R1bGVfZXZhbHsgbWl4aW4gb3RoZXIgfQ0KICBlbmQN
CmVuZA0KY2xhc3MgTW9kdWxlDQogIGRlZiBtaXhpbiBvdGhlcg0KICAgIG90
aGVyLm1vZHVsZV9ldmFseyBpbmNsdWRlIE1peGFibGUgfSB1bmxlc3MgDQog
ICAgICBNaXhhYmxlID4gb3RoZXINCiAgICBpbmNsdWRlIG90aGVyDQogIGVu
ZA0KZW5kDQoNCg0KaWYgX19GSUxFX18gPT0gJDANCiMNCiMgZXhhbXBsZSAx
IC0gc2ltcGxlIHVzYWdlDQojDQogIG1vZHVsZSBNDQogICAgaW5jbHVkZSBN
aXhhYmxlDQogICAgbW9kdWxlIENsYXNzTWV0aG9kcw0KICAgICAgZGVmIGZv
bygpIDQyIGVuZA0KICAgIGVuZA0KICBlbmQNCiAgY2xhc3MgQw0KICAgIGlu
Y2x1ZGUgTQ0KICBlbmQNCiAgcCBDLmZvbyAjPT4gNDIgDQoNCiMNCiMgZXhh
bXBsZSAyIC0gbm90ZSB0aGUgaG93IGl0IHdvcmtzIHJlY3Vyc2l2ZWx5DQoj
DQogIG1vZHVsZSBBDQogICAgaW5jbHVkZSBNaXhhYmxlDQogICAgbW9kdWxl
IENsYXNzTWV0aG9kcw0KICAgICAgZGVmIGJhcigpICdmb3J0eS10d28nIGVu
ZA0KICAgIGVuZA0KICAgIG1vZHVsZSBJbnN0YW5jZU1ldGhvZHMNCiAgICAg
IGRlZiBmb29iYXIoKSA0Mi4wIGVuZA0KICAgIGVuZA0KICBlbmQNCiAgbW9k
dWxlIEINCiAgICBpbmNsdWRlIEENCiAgZW5kDQogIGNsYXNzIEsNCiAgICBp
bmNsdWRlIEIgIyBhbmQgcmVjdXJpdmVseSBhZGQgQ2xhc3NNZXRob2RzIGZy
b20gQSENCiAgZW5kDQogIHAgSy5iYXIgICAgICAgICM9PiAnZm9ydHk9dHdv
Jw0KICBwIEsubmV3LmZvb2JhciAjPT4gNDIuMA0KDQojDQojIGV4YW1wbGUg
MyAtIHdlIG5lZWRuJ3QgYm90aCB3aXRoIE1peGFibGUgaWYgdGhlICdpbmNs
dWRlZScgc3BlY2lmaWVzIHRoYXQgaXQNCiMgd2FudHMgdG8gdG8gYSBtaXhp
bg0KIw0KICBtb2R1bGUgTQ0KICAgIG1vZHVsZSBDbGFzc01ldGhvZHMNCiAg
ICAgIGRlZiBiYXIoKSA0Mi4wIGVuZA0KICAgIGVuZA0KICAgIGRlZiBmb28o
KSA0MiBlbmQNCiAgZW5kDQogIGNsYXNzIEMNCiAgICBtaXhpbiBNDQogIGVu
ZA0KICBwIEMuYmFyICAgICAjPT4gNDIuMA0KICBwIEMubmV3LmZvbyAjPT4g
NDINCg0KIw0KIyBhbmQsIG9mIGNvdXJzZSwgaXQgd29ya3Mgd2l0aCBvYmpl
Y3RzDQojDQogIG1peGluIE0NCiAgcCBmb28gIz0+IDQyDQogIGNsYXNzIDw8
IHNlbGYNCiAgICBwIGJhciAjPT4gNDIuMA0KICBlbmQNCg0KZW5kDQoNCg==

---1400102478-735090016-1150308539=:4620--
---1400102478-735090016-1150308539=:4620--