ch01-12: clean up by @eumiro

12-seq-hacking/vector_v3.py

@@ -0,0 +1,235 @@
+"""
+A multi-dimensional ``Vector`` class, take 3
+
+A ``Vector`` is built from an iterable of numbers::
+
+    >>> Vector([3.1, 4.2])
+    Vector([3.1, 4.2])
+    >>> Vector((3, 4, 5))
+    Vector([3.0, 4.0, 5.0])
+    >>> Vector(range(10))
+    Vector([0.0, 1.0, 2.0, 3.0, 4.0, ...])
+
+
+Tests with 2-dimensions (same results as ``vector2d_v1.py``)::
+
+    >>> v1 = Vector([3, 4])
+    >>> x, y = v1
+    >>> x, y
+    (3.0, 4.0)
+    >>> v1
+    Vector([3.0, 4.0])
+    >>> v1_clone = eval(repr(v1))
+    >>> v1 == v1_clone
+    True
+    >>> print(v1)
+    (3.0, 4.0)
+    >>> octets = bytes(v1)
+    >>> octets
+    b'd\\x00\\x00\\x00\\x00\\x00\\x00\\x08@\\x00\\x00\\x00\\x00\\x00\\x00\\x10@'
+    >>> abs(v1)
+    5.0
+    >>> bool(v1), bool(Vector([0, 0]))
+    (True, False)
+
+
+Test of ``.frombytes()`` class method:
+
+    >>> v1_clone = Vector.frombytes(bytes(v1))
+    >>> v1_clone
+    Vector([3.0, 4.0])
+    >>> v1 == v1_clone
+    True
+
+
+Tests with 3-dimensions::
+
+    >>> v1 = Vector([3, 4, 5])
+    >>> x, y, z = v1
+    >>> x, y, z
+    (3.0, 4.0, 5.0)
+    >>> v1
+    Vector([3.0, 4.0, 5.0])
+    >>> v1_clone = eval(repr(v1))
+    >>> v1 == v1_clone
+    True
+    >>> print(v1)
+    (3.0, 4.0, 5.0)
+    >>> abs(v1)  # doctest:+ELLIPSIS
+    7.071067811...
+    >>> bool(v1), bool(Vector([0, 0, 0]))
+    (True, False)
+
+
+Tests with many dimensions::
+
+    >>> v7 = Vector(range(7))
+    >>> v7
+    Vector([0.0, 1.0, 2.0, 3.0, 4.0, ...])
+    >>> abs(v7)  # doctest:+ELLIPSIS
+    9.53939201...
+
+
+Test of ``.__bytes__`` and ``.frombytes()`` methods::
+
+    >>> v1 = Vector([3, 4, 5])
+    >>> v1_clone = Vector.frombytes(bytes(v1))
+    >>> v1_clone
+    Vector([3.0, 4.0, 5.0])
+    >>> v1 == v1_clone
+    True
+
+
+Tests of sequence behavior::
+
+    >>> v1 = Vector([3, 4, 5])
+    >>> len(v1)
+    3
+    >>> v1[0], v1[len(v1)-1], v1[-1]
+    (3.0, 5.0, 5.0)
+
+
+Test of slicing::
+
+    >>> v7 = Vector(range(7))
+    >>> v7[-1]
+    6.0
+    >>> v7[1:4]
+    Vector([1.0, 2.0, 3.0])
+    >>> v7[-1:]
+    Vector([6.0])
+    >>> v7[1,2]
+    Traceback (most recent call last):
+      ...
+    TypeError: 'tuple' object cannot be interpreted as an integer
+
+
+Tests of dynamic attribute access::
+
+    >>> v7 = Vector(range(10))
+    >>> v7.x
+    0.0
+    >>> v7.y, v7.z, v7.t
+    (1.0, 2.0, 3.0)
+
+
+Dynamic attribute lookup failures::
+
+    >>> v7.k
+    Traceback (most recent call last):
+      ...
+    AttributeError: 'Vector' object has no attribute 'k'
+    >>> v3 = Vector(range(3))
+    >>> v3.t
+    Traceback (most recent call last):
+      ...
+    AttributeError: 'Vector' object has no attribute 't'
+    >>> v3.spam
+    Traceback (most recent call last):
+      ...
+    AttributeError: 'Vector' object has no attribute 'spam'
+
+
+Tests of preventing attributes from 'a' to 'z'::
+
+    >>> v1.x = 7
+    Traceback (most recent call last):
+      ...
+    AttributeError: readonly attribute 'x'
+    >>> v1.w = 7
+    Traceback (most recent call last):
+      ...
+    AttributeError: can't set attributes 'a' to 'z' in 'Vector'
+
+Other attributes can be set::
+
+    >>> v1.X = 'albatross'
+    >>> v1.X
+    'albatross'
+    >>> v1.ni = 'Ni!'
+    >>> v1.ni
+    'Ni!'
+
+"""
+
+from array import array
+import reprlib
+import math
+import operator
+
+
+class Vector:
+    typecode = 'd'
+
+    def __init__(self, components):
+        self._components = array(self.typecode, components)
+
+    def __iter__(self):
+        return iter(self._components)
+
+    def __repr__(self):
+        components = reprlib.repr(self._components)
+        components = components[components.find('['):-1]
+        return 'Vector({})'.format(components)
+
+    def __str__(self):
+        return str(tuple(self))
+
+    def __bytes__(self):
+        return (bytes([ord(self.typecode)]) +
+                bytes(self._components))
+
+    def __eq__(self, other):
+        return tuple(self) == tuple(other)
+
+    def __abs__(self):
+        return math.sqrt(sum(x * x for x in self))
+
+    def __bool__(self):
+        return bool(abs(self))
+
+    def __len__(self):
+        return len(self._components)
+
+    def __getitem__(self, key):
+        if isinstance(key, slice):
+            cls = type(self)
+            return cls(self._components[key])
+        index = operator.index(key)
+        return self._components[index]
+
+# tag::VECTOR_V3_GETATTR[]
+    shortcut_names = 'xyzt'
+
+    def __getattr__(self, name):
+        cls = type(self)  # <1>
+        if len(name) == 1:  # <2>
+            pos = cls.shortcut_names.find(name)  # <3>
+            if 0 <= pos < len(self._components):  # <4>
+                return self._components[pos]
+        msg = '{.__name__!r} object has no attribute {!r}'  # <5>
+        raise AttributeError(msg.format(cls, name))
+# end::VECTOR_V3_GETATTR[]
+
+# tag::VECTOR_V3_SETATTR[]
+    def __setattr__(self, name, value):
+        cls = type(self)
+        if len(name) == 1:  # <1>
+            if name in cls.shortcut_names:  # <2>
+                error = 'readonly attribute {attr_name!r}'
+            elif name.islower():  # <3>
+                error = "can't set attributes 'a' to 'z' in {cls_name!r}"
+            else:
+                error = ''  # <4>
+            if error:  # <5>
+                msg = error.format(cls_name=cls.__name__, attr_name=name)
+                raise AttributeError(msg)
+        super().__setattr__(name, value)  # <6>
+
+# end::VECTOR_V3_SETATTR[]
+
+    @classmethod
+    def frombytes(cls, octets):
+        typecode = chr(octets[0])
+        memv = memoryview(octets[1:]).cast(typecode)
+        return cls(memv)