From: ts <decoux@...>
Date: 2005-11-26T01:28:28+09:00
Subject: Re: Dynamic finding of missing constants.

>>>>> "O" == Ola Bini <Ola.Bini@ki.se> writes:

O> I'm doing some slightly interesting things with Ruby, and I wanted to know 
O> of there's a language way of interrupting the process for finding a 
O> Constant name, like the method_missing method.

 You have Module#const_missing

moulon% ri Module#const_missing
--------------------------------------------------- Module#const_missing
     mod.const_missing(sym)    => obj
------------------------------------------------------------------------
     Invoked when a reference is made to an undefined constant in _mod_.
     It is passed a symbol for the undefined constant, and returns a
     value to be used for that constant. The following code is a (very
     bad) example: if reference is made to an undefined constant, it
     attempts to load a file whose name is the lowercase version of the
     constant (thus class +Fred+ is assumed to be in file +fred.rb+). If
     found, it returns the value of the loaded class. It therefore
     implements a perverse kind of autoload facility.

       def Object.const_missing(name)
         @looked_for ||= {}
         str_name = name.to_s
         raise "Class not found: #{name}" if @looked_for[str_name]
         @looked_for[str_name] = 1
         file = str_name.downcase
         require file
         klass = const_get(name)
         return klass if klass
         raise "Class not found: #{name}"
       end

moulon% 


Guy Decoux