Harmonize docstrings. Move redemo from Tools/scripts to Tools/demo. Add a README file to Tools/demo.
diff --git a/Tools/demo/vector.py b/Tools/demo/vector.py
new file mode 100755
index 0000000..da5b389
--- /dev/null
+++ b/Tools/demo/vector.py
@@ -0,0 +1,74 @@
+#!/usr/bin/env python3
+
+"""
+A demonstration of classes and their special methods in Python.
+"""
+
+class Vec:
+ """A simple vector class.
+
+ Instances of the Vec class can be constructed from numbers
+
+ >>> a = Vec(1, 2, 3)
+ >>> b = Vec(3, 2, 1)
+
+ added
+ >>> a + b
+ Vec(4, 4, 4)
+
+ subtracted
+ >>> a - b
+ Vec(-2, 0, 2)
+
+ and multiplied by a scalar on the left
+ >>> 3.0 * a
+ Vec(3.0, 6.0, 9.0)
+
+ or on the right
+ >>> a * 3.0
+ Vec(3.0, 6.0, 9.0)
+ """
+ def __init__(self, *v):
+ self.v = list(v)
+
+ @classmethod
+ def fromlist(cls, v):
+ if not isinstance(v, list):
+ raise TypeError
+ inst = cls()
+ inst.v = v
+ return inst
+
+ def __repr__(self):
+ args = ', '.join(repr(x) for x in self.v)
+ return 'Vec({})'.format(args)
+
+ def __len__(self):
+ return len(self.v)
+
+ def __getitem__(self, i):
+ return self.v[i]
+
+ def __add__(self, other):
+ # Element-wise addition
+ v = [x + y for x, y in zip(self.v, other.v)]
+ return Vec.fromlist(v)
+
+ def __sub__(self, other):
+ # Element-wise subtraction
+ v = [x - y for x, y in zip(self.v, other.v)]
+ return Vec.fromlist(v)
+
+ def __mul__(self, scalar):
+ # Multiply by scalar
+ v = [x * scalar for x in self.v]
+ return Vec.fromlist(v)
+
+ __rmul__ = __mul__
+
+
+def test():
+ import doctest
+ doctest.testmod()
+
+test()