From: Robert Klemme <shortcutter@...>
Date: 2009-12-29T23:37:42+09:00
Subject: Re: Using #include at the instance level?

2009/12/29 Intransition <transfire@gmail.com>:
>
>
> On Dec 29, 3:29 am, Robert Klemme <shortcut...@googlemail.com> wrote:
>> 2009/12/29 Intransition <transf...@gmail.com>:
>>
>>
>>
>> > I would like to use #include at an instance level, such that it
>> > behaves just as it does at a class level. After a number of
>> > experiments I thought for sure it would work if I ran the include
>> > through the object's singleton. Alas, submodules remain inaccessible,
>> > eg.
>>
>> >  module M
>> >    def m1; "m1"; end
>> >    module N
>> >      def self.n1; "n1"; end
>> >    end
>> >  end
>>
>> >  class X
>> >    def initialize(*mods)
>> >      (class << self; self; end).class_eval do
>> >        include *mods
>> >      end
>> >    end
>> >    def m ; m1 ; end
>> >    def n ; N.n1 ; end
>>
>> Hm, this method above won't work as scope resolution rules for
>> constants are different.
>>
>> >  end
>>
>> >  x = X.new(M)
>> >  p x.m
>> >  p x.n    #=> uninitialized constant X::N (NameError)
>>
>> > Is there any way to achieve this?
>>
>> Did you consider using #extend?
>>
>>  class X
>>    def initialize(*mods)
>>      extend *mods
>>    end
>> end
>>
>> What do you really want to achieve?  Do you have a more telling example?
>
> It's for encapsulating test cases. Eg.
>
>  TestCase.new(SomeClass) do
>    ...
>  end
>
> Within the test case block it would help to handle #include, to make
> tests less verbose.

I see to be a bit slow today: how do you want to use modules there?
Do you want to include them in the test code?  What about:

class TestCase
  def new(cl, &bl)
     @cl = cl
     instance_eval(&bl)
  end

  alias include extend
end

TestCase.new String do
  extend Foo
  include Bar
end

> Instead of making an instance of TestCase for each case, at this point
> it looks like I'll have to create a new subclass of it.

Sorry, you lost me here.

Cheers

robert


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