From: Michael Neumann <mneumann@...>
Date: 2005-01-06T11:54:38+09:00
Subject: Re: Seeking info on keyword parameters

itsme213 wrote:
> "Yukihiro Matsumoto" <matz@ruby-lang.org> wrote in message
> 
> 
>>|If a subclass of Symbol like SelectorSymbol also had a @namespace slot to
>>|provide selector namespaces (which would be great with Ruby's modules and
>>|re-opening of classes; SmallScript does something similar), we would also
>>|need some way to associate a namespace with a selector symbol. e.g.
>>|    x.send :move  # which namespace? symbol or selector symbol?
>>|    x.send N1::move # ah, N1's :move selector symbol
>>|    x.send :move # send could treat :move symbol as default_ns::move
>>|selector symbol?
>>
>>I'm not sure I get you, but I feel like you're suggesting something
>>interesting.  Let me consider.  Detailed explanation would be welcomed.
> 
> 
> When defining a method (via def... or define_method) we need to indicate
> which namespace the selector belongs to; and when invoking a method via
> x.send or x.foo, we need to indicate which namespace selector we are using.
> 
> --------------
> First for invocations of the form:  x.send(selector, *args)
> #send needs to know the namespace of the selector so it can lookup the
> correct method. A subclass of Symbol, say SelectorSymbol, could have a
> @namespace slot. NameSpace#lookup(symbol) could return a SelectorSymbol, and
> all methods (or unbound methods) could be indexed by SelectorSymbols.
> 
> So I can now write in verbose form:
>     x.send my_namespace.lookup(:move) other_args
> 
> We need a better syntax to indicate which namespace. Something like:
>     x.send myns::move other_args  # :: resolves to a SelectorSymbol
> or
>     x.send myns:.move other_args  # :. resolves to a SelectorSymbol

Why not use blocks that change what the current namespace is?

   namespace(:myns) {
     x.send :move otherargs
     ...
   }

That should be thread-local of course. Everything inside the block is 
executed in the :myns namespace.

Regards,

   Michael