From: Chris Pine <nemo@...>
Date: 2003-02-11T04:52:57+09:00
Subject: Re: everything is an object... right?

I'm not really sure why I didn't just use irb in the first place... sorry.

Anyway, I mostly answered my own question.  Just in case anyone else is
wondering:

The first thing to realize is that when you create an instance method, the
associated object would not be a Method, but an UnboundMethod.  For example:

  irb(main):001:0> class Foo
  irb(main):002:1>   def foo; 'foo'; end
  irb(main):003:1> end
  => nil
  irb(main):004:0> Foo.instance_method(:foo)
  => #<UnboundMethod: Foo#foo>
  irb(main):005:0> Foo.instance_method(:foo).id
  => 537250374
  irb(main):006:0> Foo.instance_method(:foo).id
  => 537244984
  irb(main):007:0> Foo.instance_method(:foo).id
  => 537202282

As you can see, I get back a different object each time, so the (unbound)
method itself is not really an object.

Same is true for bound methods:

  irb(main):009:0> x = Foo.new
  => #<Foo:0x400911cc>
  irb(main):010:0> x.method(:foo).id
  => 537158072
  irb(main):011:0> x.method(:foo).id
  => 537149042


However, if I were to get an instance of Method or UnboundMethod (I don't
want to call them "methods", because they really aren't methods, they are
objects associated with those methods), and then redefine the method they
associate with, they still refer to the original methods.  So it's almost
like they are real methods.  In fact, if calling `x.method(:foo).id'
returned the same object each time (assuming `foo' hadn't been redefined),
they basically *would* be real methods, wouldn't they?  I mean, methods
would essentially be real objects.  I think.

Well, I guess they still wouldn't show up in ObjectSpace.each_object...
would they?  Hmmm... Is there a reason they weren't made real objects?  It
seems like they came awfully close.

But now I have more questions...

First, is there a way to get the Method object for the method being
executed?

Second, why doesn't this work?

  irb(main):001:0> class Foo
  irb(main):002:1>   def foo; 'foo'; end
  irb(main):003:1> end
  => nil
  irb(main):004:0> x = Foo.new
  => #<Foo:0x400bc178>
  irb(main):005:0> def x.foo; 'bar'; end
  => nil
  irb(main):006:0> Foo.instance_method(:foo).bind(x)
  TypeError: method `foo' overridden
          from (irb):6:in `bind'
          from (irb):6

It works if I don't define x.foo first.

Chris