From: Eric Mahurin <eric_mahurin@...>
Date: 2005-08-26T01:44:27+09:00
Subject: Re: idea: klass.from_s(str)

--- "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">





		
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