From: Dave Burt <dave@...>
Date: 2005-10-25T11:42:02+09:00
Subject: Re: String as Subclass of Symbol?

> Has it ever been considered making String a de-immutablized subclass of
> Symbol? Would this allow for a natural coersion of Symbols to Strings,
> akin to Integer to Float? The above is a common enough occurance. And

Love your crazy ideas!

The main problem I see with this idea is that for "String < Symbol", a 
string must be expected to behave polymorphically like a symbol. Now, the 
only behaviour missing is immutability (I don't think the two methods 
id2name and to_int present an issue), but that's different enough -- if 
you're expecting an immutable symbol, what happens if it changes? (This is 
pertinent for hash keys, for example.)

Now, Symbol < String actually makes sense to me, despite all the extra 
methods. Symbol could redefine most of the methods in 
(String.instance_methods - Symbol.instance_methods) to return a new mutable 
string. That would give your proposed automatic conversion. But this still 
leaves the problem of the behaviour of the mutator methods, <<, gsub!, et. 
al. -- these cannot work properly on a symbol; they'd have to be undefined 
or raise a NotImplementedError.

And I think that works OK, and it's backwards-compatible except for:
  if var.kind_of?(String) then var.chomp! end
and possibly
  begin
    var.chomp!
  rescue NoMethodError
  end

Cheers,
Dave