From: Gavin Sinclair <gsinclair@...>
Date: 2003-11-30T15:25:13+09:00
Subject: Re: class << x

On Sunday, November 30, 2003, 2:57:07 PM, Greg wrote:

> I didn't ask what it does. I understand perfectly what "class << x" does
> and how it works and all about anonymous classes. What I asked was, why
> is the syntax "class << x"? Is there a reason? Why "class << x"?

When I was a newbie, I accepted

  o = Object.new

  class << o
    ...
  end

perfectly well.  I didn't have a way to "read" it, but I was happy
with the syntax.  It took a bit of mental gymnastics to understand

  class A
    class << self
      ...
    end
  end

but I wouldn't sacrifice the unity of concept (a class is an object)
for anything.

To summarise: I've never been put out by the syntax that Ruby has to
offer in this regard, and see no need for an alternative.

The alternative you offer is invalid, because it treads on a valid
concept in Ruby: classes within classes.

  class A
    class A
      puts self.to_s            # "A::A"
    end
  end

And the other thing you offer I find confusing:

  b = B.new
  class b.class
    def f
      ...
    end
  end

I expected this to add a method to B (the class, not the object), but
it was a syntax error.  Why?  b.class evaluates to B, and class B is
valid.  Oh well.  Anyway, I hope I've demonstrated why it doesn't
communicate with me what you want it to.

To summarise, again.  The issues that you raise are certainly things
that need to be explained to newbies quite often.  Normally, that
would reasonably be seen as a problem with the language.  In this
case, however, I think the language has it right and everybody needs
to adjust their thinking.

Cheers,
Gavin