updated contents from Atlas repo

classes/vector_v3_slots.py

@@ -0,0 +1,125 @@
+"""
+A 2-dimensional vector class
+
+    >>> v1 = Vector(3, 4)
+    >>> x, y = v1  #<1>
+    >>> x, y
+    (3.0, 4.0)
+    >>> v1  #<2>
+    Vector(3.0, 4.0)
+    >>> v1_clone = eval(repr(v1))  #<3>
+    >>> v1 == v1_clone
+    True
+    >>> print(v1)  #<4>
+    (3.0, 4.0)
+    >>> octets = bytes(v1)  #<5>
+    >>> octets
+    b'\\x00\\x00\\x00\\x00\\x00\\x00\\x08@\\x00\\x00\\x00\\x00\\x00\\x00\\x10@'
+    >>> abs(v1)  #<6>
+    5.0
+    >>> bool(v1), bool(Vector(0, 0))  #<7>
+    (True, False)
+
+Test of .frombytes() class method:
+
+    >>> v1_clone = Vector.frombytes(bytes(v1))
+    >>> v1_clone
+    Vector(3.0, 4.0)
+    >>> v1 == v1_clone
+    True
+
+# BEGIN VECTOR_V3_DEMO
+Test of `x` and `y` read-only properties:
+
+    >>> v1.x, v1.y
+    (3.0, 4.0)
+    >>> v1.x = 123
+    Traceback (most recent call last):
+      ...
+    AttributeError: can't set attribute
+
+# END VECTOR_V3_HASH_DEMO
+
+# BEGIN VECTOR_V3_HASH_DEMO
+
+    >>> v1 = Vector(3, 4)
+    >>> v2 = Vector(3.1, 4.2)
+    >>> hash(v1), hash(v2)
+    (7, 384307168202284039)
+    >>> set([v1, v2])
+    {Vector(3.1, 4.2), Vector(3.0, 4.0)}
+
+# END VECTOR_V3_DEMO
+
+
+"""
+
+from array import array
+import math
+
+# BEGIN VECTOR_V3_SLOTS
+class Vector:
+    __slots__ = ('__x', '__y')
+
+    typecode = 'd'
+
+    # methods follow (omitted in book listing)
+# END VECTOR_V3_SLOTS
+
+    def __init__(self, x, y):
+        self.__x = float(x)
+        self.__y = float(y)
+
+    @property
+    def x(self):
+        return self.__x
+
+    @property
+    def y(self):
+        return self.__y
+
+    def __iter__(self):
+        return (i for i in (self.x, self.y))  # <6>
+
+    def __repr__(self):
+        return 'Vector({!r}, {!r})'.format(*self)
+
+    def __str__(self):
+        return str(tuple(self))
+
+    def __bytes__(self):
+        return bytes(array(Vector.typecode, self))
+
+    def __eq__(self, other):
+        return tuple(self) == tuple(other)
+
+# BEGIN VECTOR_V3_HASH
+    def __hash__(self):
+        return hash(self.x) ^ hash(self.y)
+# END VECTOR_V3_HASH
+
+    def __abs__(self):
+        return math.hypot(self.x, self.y)
+
+    def __bool__(self):
+        return bool(abs(self))
+
+    def angle(self):
+        return math.atan2(self.y, self.x)
+
+    def __format__(self, fmt_spec=''):
+        if fmt_spec.endswith('p'):
+            fmt_spec = fmt_spec[:-1]
+            coords = (abs(self), self.angle())
+            outer_fmt = '<{}, {}>'
+        else:
+            coords = self
+            outer_fmt = '({}, {})'
+        components = (format(c, fmt_spec) for c in coords)
+        return outer_fmt.format(*components)
+
+    @classmethod
+    def frombytes(cls, octets):
+        arr = array(Vector.typecode)
+        arr.frombytes(octets)
+        return cls(*arr)