From: "Chr. Rippel" <chr_news@...>
Date: 2001-12-30T10:17:39+09:00
Subject: [ruby-talk:29679] Re: special case?

> > irb(main):001:0> class << 1
> > irb(main):002:1> def meth
> > irb(main):003:2> end
> > irb(main):004:1> end
> > TypeError: no virtual class for Fixnum
> >         from (irb):1
....
> It's rather a hole. The current implementation of
> primitive types does not lend itself well to singletons.
> (I think it's just Fixnum, true, false, and nil that can't
> have singletons.)
That isn't quite correct:

def nil.yes; end
puts nil.singleton_methods # => yes

On the other hand

class << nil; end
def 1.yes; end

both raise exceptions ...


> I believe this will change in the future, from what I've
> heard Matz say in the past.
Bignums (and Floats) already have singletons but they are
somewhat useless. For example,

a = 2<< 34
aa = 2<< 34

yields

p (a.equal? aa) # => false

thus even if you define

def a.yes; end

you cannot call

aa.yes

Something like ``approximate singleton classes'' would probably
more useful (especially for Floats) but probably difficult to
implement.

....
/Christoph