From: Eric Mahurin <eric_mahurin@...>
Date: 2005-08-26T01:57:00+09:00
Subject: Re: idea: klass.from_s(str)



--- Eric Mahurin <eric_mahurin@yahoo.com> wrote:

> --- "Kroeger Simon (ext)" <simon.kroeger.ext@siemens.com>
> wrote:
> 
> > 
> > > [...]
> > > If you have a klass#to_* method, you should have a
> > > corresponding klass.from_* method if appropriate.  This
> > would
> > > make your class more encapsulated, instead of having some
> > of it
> > > in String (or whatever class you are converting from).
> > 
> > Perhaps implement a method_missing in String such as
> s.to_xxx
> > 
> > will call xxx.from_s ?
> > 
> > cheers
> > 
> > Simon
> 
> 
> That sounds like a good idea to add a little convienence. 
> That
> shows the power of starting with the xxx.from_s(str) method
> instead of String#to_xxx where the class is
> embedded/abbreviated in the method name.
> 
> Here's a demo:
> 
> class String
>   def method_missing(meth)
>     if m = /^to_(.*)$/.match(meth.to_s)
>       Class.const_get(m[1].capitalize.to_sym).from_s(self)
>     else
>       super
>     end
>   end
> end
> 
> class Abc
>   def self.from_s(s)
>     self.new(s)
>   end
>   def initialize(s)
>     @abc = s
>   end
>   def to_s
>     @abc.to_s
>   end
> end
> 
> Abc.from_s("hello") # => #<Abc:0x285c7e0 @abc="hello">
> "hello".to_abc      # => #<Abc:0x285c7e0 @abc="hello">

Maybe this would be better - making the class an argument
rather than embedding it in the method name:

class String
  def to(klass)
    klass.from_s(self)
  end
end

Abc.from_s("hello") # => #<Abc:0x285c7e0 @abc="hello">
"hello".to(Abc)     # => #<Abc:0x285c7e0 @abc="hello">



__________________________________________________
Do You Yahoo!?
Tired of spam?  Yahoo! Mail has the best spam protection around 
http://mail.yahoo.com