From: Jeffrey Moss <jeff@...>
Date: 2005-07-29T04:15:22+09:00
Subject: Re: method_missing crazyness

I think optional type checking, key word being optional, would actually 
compliment the duck typing, the method with no type(s) in the argument list 
would become the default. Adding a type would only make it more specific, a 
shortcutted form of "return custom_string_method if param.is_a?(String)". 
It would come in handy more in the complex class structures than the simple 
"method_missing" case. In the case of the complex class structure, instead 
of being a substitute for the switch or conditional statement in 
method_missing, it would be a substitute for this:

def custom_string_method(obj)
    # do custom stuff on a string
end

def custom_method(obj)
    next_method_name = "custom_#{obj.class.to_s.downcase}_method"
    if self.respond_to?(next_method_name)
        return self.send(next_method_name, obj)
    end
    # do default custom stuff
end

Which would allow you to override methods for certain objects without 
overriding custom_method and adding new conditionals. If you weren't using 
method overrides, it would only be syntactical sugar, but in this case it 
actually cleans up the app a bit to say:

def custom_method(String obj)
    # do custom stuff on a string
end

def custom_method(obj)
    # do default custom stuff
end

-Jeff

----- Original Message ----- 
From: "Dave Fayram" <dfayram@gmail.com>
To: "ruby-talk ML" <ruby-talk@ruby-lang.org>
Sent: Thursday, July 28, 2005 12:16 PM
Subject: Re: method_missing crazyness


On 7/28/05, Jeffrey Moss <jeff@opendbms.com> wrote:
> Multimethods with optional typed argument lists would be totally awesome. 
> It
> wouldn't break backward compatibility either. Wasn't that the most popular
> requested feature for ruby 2?

Aren't these against the spirit of duck typing, though? I thought that
Ruby was moving away from needing type-checking dispatch rather than
towards needing it.

The only time I've ever needed it is when I was doing some heavy math
code. When your set of types is small and well known, it is much more
elegant than loading up on the to_somethings or making a kind_of? if
statement clause.

>
> As for the method_missing trick, I think it is too much of a special case,
> because what if you want to use a custom prefix instead?
>

I would venture to say special prefixes or suffixes are actually the
common case.

-- 
-- 
Dave Fayram (II)
dfayram@gmail.com