From: "Paulo Köch" <paulo.koch@...>
Date: 2006-12-28T13:05:51+09:00
Subject: Re: override.rb

Holy cow!

Tell me, what do you want us to do with this, exactly? What are you
challenging us to? Didn't get it. =/

On 12/28/06, ara.t.howard@noaa.gov <ara.t.howard@noaa.gov> wrote:
>
> since the threads split all over the place i figured i'd start yet another.
> can people break this?
>
>
> harp:~ > cat a.rb
> class Module
>    module OverRiding
>      class << self
>        def new
>          Module.new{
>            @added_methods = []
>            @parent = nil
>
>            class << self
>              attr :added_methods
>              attr :parent
>
>              def method_added m
>                super if defined? super
>              ensure
>                added_methods << m.to_s
>              end
>
>              def remove_method m
>                super if defined? super
>              ensure
>                added_methods.delete_at(added_methods.rindex(m.to_s)) rescue nil
>              end
>
>              def add_parent m
>                include(@parent = m)
>              end
>
>              def cache mname, m
>                mname = mname.to_s
>                const = mname.gsub(%r/[!]/,'__bang__').gsub(%r/[?]/,'__what__').upcase
>                const_set const, m
>
>                module_eval <<-code
>                  def #{ mname } *a, &b
>                    #{ const }.bind(self).call *a, &b
>                  end
>                code
>              end
>
>              def walking_up
>                m = self
>                loop{
>                  yield m
>                  break unless((m=m.parent) rescue nil)
>                }
>              end
>            end
>          }
>        end
>      end
>    end
>
>    def overriding &b
>      this = self
>      m = OverRiding.new
>      m.module_eval &b
>
>      unless defined? @overriding
>        @overriding = OverRiding.new
>        m.added_methods.each do |mname|
>          @overriding.cache mname, this.instance_method(mname)
>          this.remove_method mname
>        end
>      end
>
>      m.add_parent @overriding
>      include m
>      @overriding = m
>    end
>    alias_method 'override', 'overriding'
>
>    def restore mname
>      if defined? @overriding
>        mname = mname.to_s
>        @overriding.walking_up do |m|
>          break( m.remove_method mname ) if m.added_methods.include?(mname)
>        end
>      end
>      instance_method mname
>    end
>
>    def restoring *a, &b
>      o = Object.new
>      sc = class << o; self; end
>      sc.module_eval{
>        instance_methods.each{|m| remove_method m unless m[/^__/] rescue nil}
>        define_method('method_missing'){|m, *a| a << m }
>      }
>      o.instance_eval &b
>      a.flatten.compact.each{|m| restore m}
>    end
> end
>
>
>
>
> if $0 == __FILE__
>    class C
>      c = new
>
>      def m() 'a' end
>      p c.m #=> 'a'
>
>      override{ def m() super + 'b' end }
>      p c.m #=> 'ab'
>
>      override{ def m() super + 'c' end }
>      p c.m #=> 'abc'
>
>      override{ def m() super + 'd' end }
>      p c.m #=> 'abcd'
>
>      restore 'm'
>      p c.m #=> 'abc'
>
>      restore 'm'
>      p c.m #=> 'ab'
>
>      restore 'm'
>      p c.m #=> 'a'
>    end
> end
>
>
> harp:~ > ruby a.rb
> "a"
> "ab"
> "abc"
> "abcd"
> "abc"
> "ab"
> "a"
>
>
> -a
> --
> if you find yourself slandering anybody, first imagine that your mouth is
> filled with excrement.  it will break you of the habit quickly enough. - the
> dalai lama
>
>