From: Hal Fulton <hal9000@...>
Date: 2003-09-11T07:15:18+09:00
Subject: Re: ANN: MetaTags 1.0

Chad Fowler wrote:
> On Thu, 11 Sep 2003, Austin Ziegler wrote:
> 
> # On Thu, 11 Sep 2003 04:05:26 +0900, Ben Giddings wrote:
> # > Richard Kilmer wrote:
> # >> Then:
> # >>   class String
> # >>     def &(klass)
> # >>       klass.from_str(self)
> # >>     end
> # >>   end
> # >> then you can do:
> # >>   c = "one hump or two" & Caml
> # > I like this better than Dave's suggestion of the Caml() function, but it
> # > is somewhat confusing.  Since the "&" is already used, I thought maybe
> # > another operator might make more sense, but I discovered that there is
> # > only a small set of operators that seem to be overloadable.  Is there a
> # > complete list somewhere of overloadable operators?
> # 
> # irb(main):001:0> "a" & "b"
> # NoMethodError: undefined method `&' for "a":String
> #         from (irb):1
> # irb(main):002:0> VERSION
> # => "1.8.0"
> # 
> 
> Did you miss the part that said 
> 
> class String
>   def &(klass)
> ....etc.
> 
> ?

I think he was responding to the part that said, "Since & is already
used..."

To play mediator and clear up any confusion (if I can get my
attributions straight!):

Someone defined an & operator.
Rich wanted something other than &.
I *think* Ben thought that Rich was saying the String#& was already
   defined; so he tried to correct him
You (Chad) thought that Ben had failed to see the definition of String#&

Now in (partial) answer to the question of what's overloadable:
1. You can only overload genuine operators/methods; not assignment,
not dot, not ::, etc. I can't remember the full list.
2. You can never overload something that is not already recognized by
the parser as an operator -- e.g. you can't create your own operators
using arbitrary punctation as in (I think) SNOBOL.

Cheers,
Hal