From: "David A. Black" <dblack@...>
Date: 2005-08-30T23:27:48+09:00
Subject: Re: Method behaves differently when called using #send

Hi --

On Tue, 30 Aug 2005, Eric Mahurin wrote:

> --- James Edward Gray II <james@grayproductions.net> wrote:
>
>> On Aug 30, 2005, at 7:53 AM, Eric Mahurin wrote:
>>
>>> Doing this would make the semantics for calling Object#send
>>> different from every other method call.
>>
>> I disagree completely.  It would make send() function THE
>> SAME as
>> every other method call.  That makes a lot of sense to me.
>>
>> James Edward Gray II
>
> We are talking about different things.  I agree that this
> proposal would make obj.send(:meth,...) and send(:meth,...)
> function just like obj.meth(...) and meth(...).  I'm talking
> about about the fact that for all other methods, whether you
> have receiver (self) or not doesn't affect the functionality -
> only whether the method can be called because of protections.
> For this particular method (send) in this proposal, it would
> somehow be able to sense whether it was called with a receiver
> or not and behave differently.

I see what you mean; it's very magic.  I can't think of a way to
implement it in Ruby, and even though someone will be able to with dl
or whatever, it will still be too magic :-)

OK, here's another idea -- truly a code-breaker, I should warn you:

   send(object, method, *args)

instead of

   object.send(method, *args)

This would, among other things, make more sense out of the use of
"send" as the method name.  It would also mean that the privacy issue
would not become a matter of syntax, but rather a matter of logic. 
And it would make send, in practice, behave the same as the dot
operator.

Here's an implementation and a tiny little test:

   class UnavailableMethodError < RuntimeError
   end

   module Kernel
     alias :oldsend :send

     def send(obj,m,*args)
       if obj.private_methods.include?(m.to_s)
         raise UnavailableMethodError,
         "private method `#{m}' called for #{obj.inspect}:#{obj.class}"
       else
         obj.oldsend(m, *args)
       end
     end

   end

   class String
     def x; end
     private :x
   end

   p send("abc",:split,//)   # ["a","b","c"]
   p send("abc",:x)          # error


David

-- 
David A. Black
dblack@wobblini.net