Optimize Node.path_from

tests/apis/wscript

@@ -56,7 +56,8 @@ def test(ctx):
 	tt('path_from', dd.path_from(pp), os.path.split(os.getcwd())[1])
 	tt('path_from (reverse)', pp.path_from(dd), '..')
 	tt('same path', pp.path_from(pp), '.')
-	tt('same_root', bld.root.path_from(bld.root), '.')
+	tt('path from root is abspath()', pp.path_from(bld.root), pp.abspath())
+	tt('root from root', bld.root.path_from(bld.root), bld.root.abspath())
 
 	tt('root height', bld.root.height(), 0)
 	tt('self height', dd.height(), len(absdir))

waflib/Node.py

@@ -430,10 +430,9 @@ class Node(object):
 
 		:param node: path to use as a reference
 		:type node: :py:class:`waflib.Node.Node`
-		:returns: the relative path
+		:returns: a relative path or an absolute one if that is better
 		:rtype: string
 		"""
-
 		c1 = self
 		c2 = node
 
@@ -461,13 +460,11 @@ class Node(object):
 			c2 = c2.parent
 
 		if c1.parent:
-			for i in range(up):
-				lst.append('..')
+			lst.extend(['..'] * up)
+			lst.reverse()
+			return os.sep.join(lst) or '.'
 		else:
-			if lst and not Utils.is_win32:
-				lst.append('')
-		lst.reverse()
-		return os.sep.join(lst) or '.'
+			return self.abspath()
 
 	def abspath(self):
 		"""