About class in module

ruby-talk
1

-- test1.rb --

class C
  def a
  end
end

class C
  def a
    puts "override"
  end
end

puts C.new.a # => override

-- test2.rb --

class C
  def a
  end
end

module M
  class C
    def a
      puts "why not override?"
    end
  end
end

include M

puts C.new.a # => nil

···

########################
# Help Me^^
########################
--
Posted via http://www.ruby-forum.com/.

2

C and C::M are two different classes. Modules work as namespaces, so that you
can have different classes with the same name, provided they're in different
modules.

Stefano

···

On Tuesday 29 July 2008, Kyung won Cheon wrote:

-- test1.rb --

class C
  def a
  end
end

class C
  def a
    puts "override"
  end
end

puts C.new.a # => override

-- test2.rb --

class C
  def a
  end
end

module M
  class C
    def a
      puts "why not override?"
    end
  end
end

include M

puts C.new.a # => nil

########################
# Help Me^^
########################

3

Kyung won Cheon wrote:

-- test1.rb --

class C
  def a
  end
end

class C
  def a
    puts "override"
  end
end

puts C.new.a # => override

-- test2.rb --

class C
  def a
  end
end

module M
  class C
    def a
      puts "why not override?"
    end
  end
end

include M

puts C.new.a # => nil

########################
# Help Me^^
########################

Hhmm, this is actually a little tricky. If I had to hazard a guess I would say it's related to the fact that modules included in X are higher in the lookup chain than X itself. e.g.:

module M
   def foo; "M-foo" end
   def foo2; "M-foo2" end
end
class A
   def foo; "A-foo" end
   include M
end
A.new.foo #=> "A-foo"
A.new.foo2 #=> "M-foo2"

so I imagine the same rule applies to constant lookups:

module N
   BAR = "N-bar"
   BAR2 = "N-bar2"
end
class B
   BAR = "B-bar"
   include N
end
B::BAR #=> "B-bar"
B::BAR2 #=> "N-bar2"

With warnings enabled, you would have seen that your test1.rb outputs:
   (irb):8: warning: method redefined; discarding old a

···

--
Daniel

4

You mean M::C.

just my 2cents, Sandor Szücs

···

On 29.07.2008, at 12:41, Stefano Crocco wrote:

C and C::M are two different classes

--