From: Ben Tompkins <nbitspoken@...>
Date: 2007-09-03T04:10:33+09:00
Subject: Re: Shouldn't it be class >> self , or am I dyslexic?

unknown wrote:
> Hi --
Perhaps you were misled by the first sentence of my reply to Sebastian, 
in which
I said 'you are basically correct to say that "self inherits from the 
singleton class.".' Note the "basically" qualification. Apart from that 
sentence, my entire exposition prior to this reply, which spans two 
postings, argues *against* the idea that "<<" signifies inheritance in:

class << object
  ...
end

In pseudocode, this translates into:

object.method1 # error
object.method2 # error

1. temp = Class.new { method1, method2, ... }
2. temp.superclass = object.class
3. object.class = temp

object.method1 # OK
object.method2 # OK

Thus 1-3 might be more succinctly expressed as:

Class.new { method1, method2 } >> object

which is very close to:

class >> object  # instead of class << object
  def method1
    ...
  end

  def method2
    ...
  end
end

Got it?

nbits








> 
> I'm sorry, but I had to chuckle at the use of the word "intuitive"
> after that explanation :-)
> 
> I wouldn't think of class << obj as having anything at all to do with
> inheritance. It's more like this, in terms of how the class keyword
> works:
> 
>    class expr
> 
> where expr can be:
> 
>    A
>    A < B
>    << arbitrary_object
> 
> So the inheritance < is more like:
> 
>    class (A < B)
> 
> and the singleton notation is more like:
> 
>    class (<< obj)
> 
> Remember, also, that the class keyword isn't itself a class
> identifier; you're not looking for "the class that is >> object", but
> the class that is, so to speak, yielded from object. (Or something.)
> It's not a notation that relates very closely to any other.
> 
> 
> David

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