example-code-2e/classes/vector2d_v0.py
2014-10-17 22:26:39 -03:00

61 lines
1.2 KiB
Python

"""
A 2-dimensional vector class
# BEGIN VECTOR2D_V0_DEMO
>>> v1 = Vector2d(3, 4)
>>> x, y = v1 #<1>
>>> x, y
(3.0, 4.0)
>>> v1 #<2>
Vector2d(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(Vector2d(0, 0)) #<7>
(True, False)
# END VECTOR2D_V0_DEMO
"""
# BEGIN VECTOR2D_V0
from array import array
import math
class Vector2d:
typecode = 'd' # <1>
def __init__(self, x, y):
self.x = float(x) # <2>
self.y = float(y)
def __iter__(self):
return (i for i in (self.x, self.y)) # <3>
def __repr__(self):
return 'Vector2d({!r}, {!r})'.format(*self) # <4>
def __str__(self):
return str(tuple(self)) # <5>
def __bytes__(self):
return bytes(array(Vector2d.typecode, self)) # <6>
def __eq__(self, other):
return tuple(self) == tuple(other) # <7>
def __abs__(self):
return math.hypot(self.x, self.y)
def __bool__(self):
return bool(abs(self)) # <8>
# END VECTOR2D_V0