ch01: automated tests

01-data-model/vector2d.py

@@ -1,3 +1,35 @@
+"""
+vector2d.py: a simplistic class demonstrating some special methods
+
+It is simplistic for didactic reasons. It lacks proper error handling,
+especially in the ``__add__`` and ``__mul__`` methods.
+
+This example is greatly expanded later in the book.
+
+Addition::
+
+    >>> v1 = Vector(2, 4)
+    >>> v2 = Vector(2, 1)
+    >>> v1 + v2
+    Vector(4, 5)
+
+Absolute value::
+
+    >>> v = Vector(3, 4)
+    >>> abs(v)
+    5.0
+
+Scalar multiplication::
+
+    >>> v * 3
+    Vector(9, 12)
+    >>> abs(v * 3)
+    15.0
+
+    
+"""
+
+
 from math import hypot
 
 class Vector: