From: "Wolfgang Nádasi-Donner" <wonado@...>
Date: 2007-01-22T01:20:06+09:00
Subject: Re: Minor Change Proposal for Classes 'Object' and 'Method'

dblack@wobblini.net schrieb:
> In any case,
> I included it because it demonstrates that there's a "meta" or
> two-step way of getting a message to an object, but that a.method(:x)
> isn't such a technique.

"mo = a.method(:x)" creates a new object "mo" of class "Method", which contains 
the object "a" and a reference (or however to name this) to a method. To find 
the method, ":x" will be interpreted as a message "x" to object "a", but the 
corresponding method will not be executed, but referenced in the new Method object.

When writing "mo.call" the object "a" will be enforced to use the method 
referenced by "mo" without any method lookup. This means, that the actual state 
of object "a" will be used to call a method, which may be overwritten in the 
meantime.

The name "receiver" for a method of class "Method", which returns the object for 
which "method" was called makes some sense, because in the moment "method" was 
called, the referenced method inside the "Method" object would be executed by 
the object when receiving the message named by the parameter for the "method" 
method.

 >>>>> Code >>>>>
class Otto
   attr_accessor :id
   def hi
     puts "'Hi!' from an instance of 'Otto' with id #{self.id}"
   end
   def initialize(id)
     self.id = id
   end
end

otto = Otto.new(42)
myhi = otto.method(:hi)

otto.hi      # => 'Hi!' from an instance of 'Otto' with id 42
myhi.call    # => 'Hi!' from an instance of 'Otto' with id 42

class Otto
   def hi
     puts "'Hihihi!' from an instance of 'Otto' with id #{self.id}"
   end
end

otto.id = 84

otto.hi      # => 'Hihihi!' from an instance of 'Otto' with id 84
myhi.call    # => 'Hi!' from an instance of 'Otto' with id 84

class Otto
   remove_method :hi
end

myhi.call    # => 'Hi!' from an instance of 'Otto' with id 84
otto.hi      # => MethodSuchReihe.rb:33: undefined method `hi' for
              # => #<Otto:0x2ae9af0 @id=84> (NoMethodError)
 >>>>> EOC >>>>>

Wolfgang N�dasi-Donner