--- a/mamba/level.py	Fri Sep 16 23:27:49 2011 +0200
+++ b/mamba/level.py	Fri Sep 16 23:28:28 2011 +0200
@@ -313,7 +313,7 @@
            exist"""
         for sprite_ascii in self.sprites_ascii:
             try:
-                pos, _sep, rest = sprite_ascii.partition(':')
+                pos, _, rest = sprite_ascii.partition(':')
                 pos = [int(x.strip()) for x in pos.split(',')]
             except ValueError:
                 continue
@@ -327,10 +327,13 @@
 
     def validate_sprite(self, sprite):
         """Check that the sprite line is valid"""
-        pos, _sep, rest = sprite.partition(':')
-        pos = [int(x.strip()) for x in pos.split(',')]
-        class_name, rest = rest.split(None, 1)
-        args = rest.split()
+        try:
+            pos, _sep, rest = sprite.partition(':')
+            pos = [int(x.strip()) for x in pos.split(',')]
+            class_name, rest = rest.split(None, 1)
+            args = rest.split()
+        except ValueError:
+            raise InvalidMapError('Unable to determine sprite parameters.')
         sprite_id, args = args[0], args[1:]
         try:
             cls = sprites.find_sprite(class_name)
@@ -339,5 +342,17 @@
         sprite = cls(*args)
         if sprite_id in self.extra_sprites:
             # Check that duplicate id is not at the same position
-            if self.extra[sprite_id].tile_pos != pos:
+            if self.extra_sprites[sprite_id].tile_pos != pos:
                 raise InvalidMapError('Duplicate sprite id: %s.' % sprite_id)
+
+    def add_sprite(self, sprite):
+        self.sprites_ascii.append(sprite)
+
+    def replace_sprite(self, sprite):
+        # Need to find the sprite at the same psoition
+        pos, _sep, rest = sprite.partition(':')
+        pos = [int(x.strip()) for x in pos.split(',')]
+        old_sprite = self.get_sprite_at(pos)
+        print sprite, old_sprite
+        self.sprites_ascii.remove(old_sprite)
+        self.sprites_ascii.append(sprite)