From: HarryO <harryo@...>
Date: 2001-11-17T04:18:36+09:00
Subject: [ruby-talk:25609] Re: Aliases for class methods

> 'alias' works on instance methods. The class methods of class 'File' are
> instance methods of File's metaclass, so we have to enter the context of
> that metaclass to alias them.

That makes sense.

>... This
> class-of-a-class is File's metaclass, and it holds all of File's class
> methods. We can get access to this class within File's class definition
> using the class <<self notation, in the same way we can get to any
> object's class using <<object.

I had a quick skim through chapter 19 and it's now as clear as mud :-).
I'll have to set aside a lot more time to get into the details.

To try to understand what you were getting at, do you mean that the
notation

    class << self
       ...
    end

simply means that the code within that block is executed within the
context of whatever object is referred to by "self"?  Given that when we
put that inside

   class File
      ...
   end

we're not inside a specific instance of File, "self" is interpreted as
the constant object that represents the class File and hence the
definition of the alias is made part of File and hence is equivalent to a
static member function in java or C++?

Can you explain why just putting the "alias original open" inside the
"class File ... end" doesn't have the desired effect?  I would have
thought that anything within that scope would be effectively the same as
putting it inside "class << self ... end".

For example, if I defineda brand new method for File, why do I not need
to put that inside "class << self ... end" for it to be added to File?

Sorry if I'm being obtuse, but I'm obviously missing some subtle distinction.