use Type objects for the types in the type hierarchy

1 files changed, 30 insertions, 13 deletions

diff --git a/TurtleArt/tatype.py b/TurtleArt/tatype.py
index 5ddff02..d4fec2b 100644
--- a/TurtleArt/tatype.py
+++ b/TurtleArt/tatype.py
@@ -27,19 +27,36 @@ from taconstants import (Color, CONSTANTS)
 from tautils import debug_output
 
 
-# types are defined as numbers because they are faster to compare than strings
-# TODO make a dict or something to convert the numbers to strings for output
-TYPE_OBJECT = 0
-TYPE_CHAR = 1
-TYPE_COLOR = 2
-TYPE_FLOAT = 3
-TYPE_INT = 4
-TYPE_NEGATIVE = 5
-TYPE_NUMBER = 6
-TYPE_NUMERIC_STRING = 7
-TYPE_POSITIVE = 8
-TYPE_STRING = 9
-TYPE_ZERO = 10
+class Type(object):
+    """ A type in the type hierarchy. The `name` attribute is only for
+    pretty-printing. The `value` attribute should be of a type that is fast
+    to compare, like e.g., int. """
+    def __init__(self, name, value):
+        self.name = name
+        self.value = value
+    def __eq__(self, other):
+        if other is None:
+            return False
+        if not isinstance(other, Type):
+            raise TypeError("cannot compare Type to object of type " +
+                            repr(type(other)))
+        return self.value == other.value
+    def __repr__(self):
+        return repr(self.name)
+    def __str__(self):
+        return str(self.name)
+
+TYPE_OBJECT = Type('object', 0)
+TYPE_CHAR = Type('char', 1)
+TYPE_COLOR = Type('color', 2)
+TYPE_FLOAT = Type('float', 3)
+TYPE_INT = Type('int', 4)
+TYPE_NEGATIVE = Type('negative', 5)
+TYPE_NUMBER = Type('number', 6)
+TYPE_NUMERIC_STRING = Type('numeric string', 7)
+TYPE_POSITIVE = Type('positive', 8)
+TYPE_STRING = Type('string', 9)
+TYPE_ZERO = Type('zero', 10)
 ARG_TYPES = (
     # possible types of arguments to Primitives
     TYPE_CHAR, TYPE_COLOR, TYPE_FLOAT, TYPE_INT, TYPE_NEGATIVE, TYPE_NUMBER,