From: Tanaka Akira <akr@...17n.org>
Date: 2002-01-12T03:29:38+09:00
Subject: [ruby-list:33321] Re: " 差分ベースモジュール " in Ruby

In article <hvog05dxxe0.fsf@coulee.a02.aist.go.jp>,
  Tanaka Akira <akr@m17n.org> writes:

> $B$$$(!"$"$k%U%!%$%k(B f $B$+$i$"$k%U%!%$%k(B g $B$r(B require $B$7$?$H$-$K$O(B g $B$GDj(B
> $B5A$5$l$?L>A0$r(B f $B$+$i;H$($k$h$&$K$9$k$3$H$rA[Dj$7$F$$$^$9!#(B
> 
> $B$D$^$j(B namespace $B$O%U%!%$%k$r%N!<%I$H$9$k(B DAG $B$K$J$j$^$9!#(B

$B$J$s$H$J$/!"4JC1$J$N$r:n$C$F$_$^$7$?!#(B

% cat main.rb                
require 'left.rb'
require 'right.rb'

c = C.new
c.l
c.r
% cat left.rb 
class C
  def l; m end
  def m; p :left_m end
end
% cat right.rb 
class C
  def r; m end
  def m; p :right_m end
end

$B$H$$$&$h$&$K(B 3$B$D$N%U%!%$%k$,$"$C$?$H$7$^$9!#$3$l$rIaDL$K<B9T$9$k$H(B

% ruby main.rb
:right_m
:right_m

$B$H$J$j$^$9!#(B

$B$,!"$3$3$G(B($B;d$N2r<a$K$h$k(B) selector namespace $B$,F3F~$7$F!"(Brequire $B$7$F(B
$B$$$J$$%U%!%$%k$N%a%=%C%I$O8+$($J$$$H9M$($k$H!"(Bleft.rb $B$H(B right.rb $B$O(B
require $B4X78$K$*$$$F;RB9(B - $BAD@h4X78$K$O$J$$$N$G!"(Bm $B$H$$$&L>A0$N%a%=%C(B
$B%I$O43>D$7$J$$$HA[A|$G$-$^$9!#$D$^$j!"(Bl $B$,8F$S=P$9(B m $B$O(B left.rb $B$N(B m
$B$K$J$j!"(Br $B$,8F$S=P$9(B m $B$O(Bright.rb $B$N(B m $B$K$J$k$@$m$&!"$H$$$&$o$1$G$9!#(B
$B$D$^$j(B

% ruby -rnamespace.rb bottom.rb
:left_m
:right_m

$B$H$$$&$h$&$J$+$s$8$G$9!#(B

$B$H!"$$$&$h$&$J$3$H$r8zN(L5;k$G<B8=$7$?(B namespace.rb $B$O<!$N$h$&$J$b$N$G(B
$B$9!#(B

% cat namespace.rb
Dependences = []
NameSpace = {}

def normalize_feature(feature)
  # xxx: this method should return absolute pathname including suffix.
  File.basename(feature, '.rb')
end

alias namespace_original_require require
def require(feature)
  depender = normalize_feature(caller.first.sub(/:.*/, ''))
  dependee = normalize_feature(feature)
  #p [:require, depender, dependee]
  Dependences << [depender, dependee]
  namespace_original_require feature
end

def search_method(file, klass, name)
  #p [:search_method, file, klass, name]
  #p Dependences
  #p NameSpace
  klass.ancestors.each {|mod|
    files = [file]
    # xxx: Dependences may have cycle.
    Dependences.each {|depender, dependee|
      next unless files.include? depender
      files << dependee
    }
    files.uniq!
    #p files
    qualified_names = []
    files.each {|f|
      if NameSpace.include? [f, mod, name]
        qualified_names << NameSpace[[f, mod, name]]
      end
    }
    qualified_names.uniq!
    case qualified_names.length
    when 0
      raise StandardError.new "internal error: no method found: #{file} #{klass} #{name}"
    when 1
      #p qualified_names.first
      return qualified_names.first
    else
      raise StandardError.new "method conflict: #{name}: #{qualified_names.join(' ')}"
    end
  }
end

class Module
  @@enable_namespace = false

  def disable_namespace
    @@enable_namespace = false
    begin
      yield
    ensure
      @@enable_namespace = true
    end
  end

  def method_added(name)
    return unless @@enable_namespace

    file = normalize_feature(caller.first.sub(/:.*/, ''))
    mod = self
    qualified_name = "_#{file}_#{mod}_#{name}"
    #p [:method_added, file, mod, name] 

    NameSpace[[file, mod, name]] = qualified_name

    disable_namespace {
      code = <<-"END"
        alias_method #{qualified_name.dump}, :#{name}
	def #{name}(*args, &block)
	  file = normalize_feature(caller.first.sub(/:.*/, ''))
	  #p [:call, file, :#{name}, args]
	  send(search_method(file, self.class, :#{name}), *args, &block)
	end
      END
      #print code
      mod.class_eval code
    }
  end

  @@enable_namespace = true
end

$B$A$J$_$K!"$3$N(B namespace.rb $B$G$O(B left.rb $B$H(B right $B$NN>J}$r(B require $B$7(B
$B$F$$$k>l=j$+$i(B m $B$r8F$V$H!"[#Kf$J$N$G%(%i!<$K$J$j$^$9!#(B
(override $B$r07$C$F$$$J$$$N$G%(%i!<$K$7$9$.$G$9$,!#(B)

% ruby -rnamespace.rb -e 'require "left"; require "right"; C.new.m'
./namespace.rb:45:in `search_method': method conflict: m: _left_C_m _right_C_m (StandardError)
        from ./namespace.rb:22:in `each'
        from ./namespace.rb:22:in `search_method'
        from (eval):5:in `m'
        from -e:1
-- 
[$BEDCf(B $BE/(B][$B$?$J$+(B $B$"$-$i(B][Tanaka Akira]
$B!V$U$($m(B! $B$o$+$a$A$c$s:n@o$G$9$(C"=$B!W(B(Little Worker, $B7KM7@84](B)