From: Dave Thomas <Dave@...>
Date: 2003-09-09T12:59:49+09:00
Subject: Re: ANN: MetaTags 1.0


On Monday, September 8, 2003, at 10:35 PM, Yukihiro Matsumoto wrote:

>
> I agree with usefulness of user-defined literals, and this is much
> disciplined than generic reader macros, but still we need to discuss
> pros and cons.
>

A suggestion for a convention: rather than go down the strange 
punctuation route (%Y{...} etc), could we just not adopt the convention 
that, where sensible, each class that can construct instances from a 
string should define a top-level method with the same name as the class.

So, if I wrote a class called Caml, I'd also define a top-level method, 
also called Caml, something like:

    class Caml
      def Caml.from_string(str)
        # .. check string format ..
        self.new(str)   # or something similar
      end
    end

    def Caml(str)
      Caml.from_string(str)
    end


Then I could get the effect of literals using:

     c = Caml "one hump or two"

If it was appropriate, the top-level method could be memoized, so we 
could chose to have new objects created on each call or one object per 
literal.


Cheers


Dave