lib/forwardable.rb

DEFINITIONS

   1  #
   2  #   forwardable.rb - 
   3  #       $Release Version: 1.1$
   4  #       $Revision: 1.2 $
   5  #       $Date: 2001/11/03 13:41:57 $
   6  #       by Keiju ISHITSUKA(keiju@ishitsuka.com)
   7  #       original definition by delegator.rb
   8  # --
   9  # Usage:
  10  #
  11  #   class Foo
  12  #     extend Forwardable
  13  #
  14  #     def_delegators("@out", "printf", "print")
  15  #     def_delegators(:@in, :gets)
  16  #     def_delegator(:@contents, :[], "content_at")
  17  #   end
  18  #   f = Foo.new
  19  #   f.printf ...
  20  #   f.gets
  21  #   f.content_at(1)
  22  #
  23  #   g = Goo.new
  24  #   g.extend SingleForwardable
  25  #   g.def_delegator("@out", :puts)
  26  #   g.puts ...
  27  #
  28  #
  29  
  30  module Forwardable
  31  
  32    @debug = nil
  33    class<<self
  34      attr_accessor :debug
  35    end
  36  
  37    def def_instance_delegators(accessor, *methods)
  38      for method in methods
  39        def_instance_delegator(accessor, method)
  40      end
  41    end
  42  
  43    def def_instance_delegator(accessor, method, ali = method)
  44      accessor = accessor.id2name if accessor.kind_of?(Integer)
  45      method = method.id2name if method.kind_of?(Integer)
  46      ali = ali.id2name if ali.kind_of?(Integer)
  47  
  48      module_eval(<<-EOS, "(__FORWARDABLE__)", 1)
  49        def #{ali}(*args, &block)
  50          begin
  51            #{accessor}.__send__(:#{method}, *args, &block)
  52          rescue Exception
  53            $@.delete_if{|s| /^\\(__FORWARDABLE__\\):/ =~ s} unless Forwardable::debug
  54            Kernel::raise
  55          end
  56        end
  57      EOS
  58    end
  59  
  60    alias def_delegators def_instance_delegators
  61    alias def_delegator def_instance_delegator
  62  end
  63  
  64  module SingleForwardable
  65    def def_singleton_delegators(accessor, *methods)
  66      for method in methods
  67        def_singleton_delegator(accessor, method)
  68      end
  69    end
  70  
  71    def def_singleton_delegator(accessor, method, ali = method)
  72      accessor = accessor.id2name if accessor.kind_of?(Integer)
  73      method = method.id2name if method.kind_of?(Integer)
  74      ali = ali.id2name if ali.kind_of?(Integer)
  75  
  76      instance_eval(<<-EOS, "(__FORWARDABLE__)", 1)
  77         def #{ali}(*args, &block)
  78           begin
  79             #{accessor}.__send__(:#{method}, *args,&block)
  80           rescue Exception
  81             $@.delete_if{|s| /^\\(__FORWARDABLE__\\):/ =~ s} unless Forwardable::debug
  82             Kernel::raise
  83           end
  84         end
  85      EOS
  86    end
  87  
  88    alias def_delegators def_singleton_delegators
  89    alias def_delegator def_singleton_delegator
  90  end
  91  
  92  
  93  
  94