Christoph a ñÄrit :
> Ara.T.Howard / noaa.gov schrieb:
> Actually the behavior is not consistent  - assuming the definition
> ----
> public # create meta objects
> def m(height =1)
>    height.zero? ? self  :   class << self; self end.m(height -1)
> end
> ----
> 
> and the natural inheritance assumption, that the class relation
> 
> X < Y         # true, implies
> X.m < Y.m # true
> ---
> you would expect the  following method lookup path for a
> singleton class of  "height" 5
> ---
> class A; end
> class B < A; end
> b = B.new
> 
> b.m(5) <- B.m(4)    < A.m(4) < Object.m(4) <
> Class.m(3) < Module.m(3) <  Object.m(3) <
> Class.m(2) < Module.m(2) <  Object.m(2) <
> Class.m     < Module.m     <  Object.m      <
> Class         <  Module        <  Object < Kernel
> ---
> 
> From a practical point of view this would be rather silly, so Matz bend
> the rules, and "benevolently ruled" the following to be true
> ---
> b.m(5) < Class.m < Module.m <  Object.m <
>              Class    <  Module     <  Object  < Kernel
> ---
> 
> I personally still prefer honest exception raising over a trickery like
> this.

What an impressive demonstration.

Let me add more precision to your affirmation:
b.m(5) < B.m(4) # => nil
B.m(4) < A.m(4) # => nil
A.m(4) < Object.m(4) # => nil
Object.m(4) < Class.m(3) # => nil
Class.m(3) < Module.m(3) # => nil
Module.m(3) <  Object.m(3) # => nil
Object.m(3) < Class.m(2) # => nil
Class.m(2) < Module.m(2) # => nil
Module.m(2) <  Object.m(2) # => nil
Object.m(2) < Class.m # => true
Class.m < Module.m # => true
Module.m < Object.m # => true
Object.m < Class # => true
Class < Module # => true
Module < Object # => true
Object < Kernel # => true

Then, we have to choose between two things: limit the "height" of singleton
class, or correct that inheritence model. I'd be for the first one.

-- 
Lionel Thiry

Personal website: http://users.skynet.be/lthiry/