From: Trans <transfire@...>
Date: 2008-09-09T10:29:23+09:00
Subject: Re: #to_self

On Sep 8, 6:21 pm, Nobuyoshi Nakada <n...@ruby-lang.org> wrote:
> Hi,
>
> At Mon, 8 Sep 2008 00:35:34 +0900,
> Trans wrote in [ruby-talk:314145]:
>
> > That could work, but if to_self is used there will be issues clearly
> > (!!!!!!!!! ain't a number). Hence, what I'm really after is an
> > optional method that can be defined when needed to say "how to become
> > grumpy". Then:
>
> Why not just override Symbol#grumpy?
>
>   module Grumpy
>     def grumpize
>       "#{to_s.upcase}!!!!!!!!!"
>     end
>   end
>
>   class String
>     include Grumpy
>   end
>
>   class Symbol
>     include Grumpy
>     def grumpize
>       super.to_sym
>     end
>   end
>
>   p "fun".grumpize  #=> "FUN!!!!!!!!!"
>   p :fun.grumpize  #=> :"FUN!!!!!!!!!"

Easy enough when you have one method. No fun with 20+.

> Or, String#try_convert is defined in 1.9:
>
>   module Grumpy
>     def grumpize
>       self.class.try_convert("#{to_s.upcase}!!!!!!!!!")
>     end
>   end
>
>   class String
>     include Grumpy
>   end
>
>   class Symbol
>     include Grumpy
>     def self.try_convert(s)
>       s.to_sym
>     end
>   end
>
>   p "fun".grumpize  #=> "FUN!!!!!!!!!"
>   p :fun.grumpize  #=> :"FUN!!!!!!!!!"

Ah, now that's interesting, and more along the lines of what I've been
pondering. This is like #to_self defined on the metaclass, which makes
sense. And is perfect use if limited to particular conversions (like
String/Symbol conversion). What is the intended purpose of
#try_convert, BTW, ie. Why was it added to 1.9?

My case still calls for a special method though, if it is to be open
for use for anything more than String/Symbol. The Integer example for
instance --a try_convert of #to_i here would be pointless for
Grumpies. The use of the special method is basically the same concept
as for Hash#<< on ruby-core where Enumerable could use an optional
enumerator/species method. Seems almost like some sort of Design
Pattern.

T.