From: ptkwt@... (Phil Tomson)
Date: 2004-09-14T10:09:54+09:00
Subject: Re: traits & roles

In article <4581.218.214.1.200.1095117526.squirrel@webmail.imagineis.com>,
Gavin Sinclair <gsinclair@soyabean.com.au> wrote:
>Phil wrote:
>> So you might have:
>>
>>   class Baz
>>   end
>>
>>   baz = Baz.new
>>   baz.extend Foo  #baz now has Foo 'traits'
>>
>> ....and later you might want to do:
>>   baz.unextend Foo #remove the Foo 'traits' from baz
>>
>> ....later on you could add another set of traits to baz:
>>   baz.extend OtherTraits
>>
>> Of course there is no 'unextend', but there are probably ways to
>> implement this.  For example, you could get a list of all of the methods
>>  of Foo and undef them in the baz object (couldn't you?)
>
>I'd expect a proper implementation of 'unextend' to just "peel away a
>layer of methods", not actually remove them.  So...
>
>  module Foo1
>    def foo; "foo1"; end
>  end
>
>  module Foo2
>    def foo; "foo2"; end
>  end
>
>  class X
>  end
>
>  x = X.new
>
>  x.foo                   # error
>
>  x.extend Foo1
>  x.foo                   # "foo1"
>
>  x.extend Foo2
>  x.foo                   # "foo2"
>
>  x.unextend Foo2
>  x.foo                   # "foo1"
>

Yes, you're right.  This would be better behavior.  Any idea how something 
like that could be implemented?

Phil