From: Harry Ohlsen <harryo@...>
Date: 2001-11-29T08:13:36+09:00
Subject: [ruby-talk:26847] Re: overload possible?

Here's a slightly better version, which also fixes the problem that
the problem that the previous one didn't return the result of running
the matching block.

It IS a little messy, though, in that you have to sacrifice a class
variable for the return value.  Hmmm ... maybe Robert's version
is looking simpler now :-).

In "overload.rb" ...

module Overload

    def signature(args, *types, &block)
        argsSignature  = (args.collect  { |a| a.type.to_s }).join("-")
        typesSignature = types.join("-")

        if argsSignature == typesSignature
            block.call(*args)
            true
        else
            false
        end
    end
 
end

Then you can write ...
 
class Fred
 
    include Overload
 
    def hello(*args)
        if signature(args, :Fixnum, :String, :Float) do
            |i, s, f|
 
            puts "(Fixnum, String, Float) -> [ #{i}, \"#{s}\", #{f} ]"
 
            @result = "1"
        end
        elsif signature(args, :String, :Fixnum) do
            |i, s|
 
            puts "(String, Fixnum) -> [ \"#{s}\", #{i} ]"
 
            @result = "2"
        end
        else
            puts "Fred.hello() -- bad set of arguments"

            @result = "3"
        end
 
        @result
    end
 
end
 
f = Fred.new
 
f1 = f.hello(123, "hello", 123.456)
f2 = f.hello("hello", 123)
f3 = f.hello("abc", "def")
 
puts "f1 = #{f1}  f2 = #{f2}  f3 = #{f3}"