diff --git a/ChangeLog b/ChangeLog
index f1bb4a6227..bc6cf96bbb 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Mon Aug 29 01:43:05 2005  Tanaka Akira  <akr@m17n.org>
+
+	* lib/pathname.rb (Pathname#descend): new method.
+	  (Pathname#ascend): ditto.
+
 Mon Aug 29 00:35:09 2005  Tanaka Akira  <akr@m17n.org>
 
 	* lib/time.rb: require 'date/format' instead of 'parsedate'.
diff --git a/lib/pathname.rb b/lib/pathname.rb
index fd7fa508b8..d9dabd0ca0 100644
--- a/lib/pathname.rb
+++ b/lib/pathname.rb
@@ -422,6 +422,74 @@ class Pathname
     @path.scan(%r{[^/]+}) { yield $& }
   end
 
+  # Iterates over and yields a new Pathname object
+  # for each element in the given path in descending order.
+  #
+  #  Pathname.new('/path/to/some/file.rb').descend {|v| p v}
+  #     #<Pathname:/>
+  #     #<Pathname:/path>
+  #     #<Pathname:/path/to>
+  #     #<Pathname:/path/to/some>
+  #     #<Pathname:/path/to/some/file.rb>
+  #
+  #  Pathname.new('path/to/some/file.rb').descend {|v| p v}
+  #     #<Pathname:path>
+  #     #<Pathname:path/to>
+  #     #<Pathname:path/to/some>
+  #     #<Pathname:path/to/some/file.rb>
+  #
+  def descend
+    paths = []
+    v = self
+    if absolute?
+      until v.root?
+        paths << v
+        v = v.dirname
+      end
+      paths << v
+    else
+      until v.to_s == '.'
+        paths << v
+        v = v.dirname
+      end
+    end
+    paths.reverse_each {|path| yield path }
+  end
+
+  # Iterates over and yields a new Pathname object
+  # for each element in the given path in ascending order.
+  #
+  #  Pathname.new('/path/to/some/file.rb').ascend {|v| p v}
+  #     #<Pathname:/path/to/some/file.rb>
+  #     #<Pathname:/path/to/some>
+  #     #<Pathname:/path/to>
+  #     #<Pathname:/path>
+  #     #<Pathname:/>
+  #
+  #  Pathname.new('path/to/some/file.rb').ascend {|v| p v}
+  #     #<Pathname:path/to/some/file.rb>
+  #     #<Pathname:path/to/some>
+  #     #<Pathname:path/to>
+  #     #<Pathname:path>
+  #
+  def ascend
+    paths = []
+    v = self
+    if absolute?
+      until v.root?
+        paths << v
+        v = v.dirname
+      end
+      paths << v
+    else
+      until v.to_s == '.'
+        paths << v
+        v = v.dirname
+      end
+    end
+    paths.each {|path| yield path }
+  end
+
   #
   # Pathname#+ appends a pathname fragment to this one to produce a new Pathname
   # object.
@@ -1203,5 +1271,33 @@ if $0 == __FILE__
       assert_equal(1, count)
       assert_equal(2, result)
     end
+
+    def test_descend_abs
+      rs = %w[/ /a /a/b /a/b/c]
+      Pathname.new("/a/b/c").descend {|v|
+        assert_equal(Pathname.new(rs.shift), v)
+      }
+    end
+
+    def test_descend_rel
+      rs = %w[a a/b a/b/c]
+      Pathname.new("a/b/c").descend {|v|
+        assert_equal(Pathname.new(rs.shift), v)
+      }
+    end
+
+    def test_ascend_abs
+      rs = %w[/a/b/c /a/b /a /]
+      Pathname.new("/a/b/c").ascend {|v|
+        assert_equal(Pathname.new(rs.shift), v)
+      }
+    end
+
+    def test_ascend_rel
+      rs = %w[a/b/c a/b a]
+      Pathname.new("a/b/c").ascend {|v|
+        assert_equal(Pathname.new(rs.shift), v)
+      }
+    end
   end
 end