cpython/Demo/classes/Vec.py

# A simple vector class


def vec(*v):
    return apply(Vec, v)


class Vec:

    def __init__(self, *v):
        self.v = []
        for x in v:
            self.v.append(x)


    def fromlist(self, v):
        self.v = []
        if type(v) <> type([]):
            raise TypeError
        self.v = v[:]
        return self


    def __repr__(self):
        return 'vec(' + `self.v`[1:-1] + ')'

    def __len__(self):
        return len(self.v)

    def __getitem__(self, i):
        return self.v[i]

    def __add__(a, b):
        # Element-wise addition
        v = []
        for i in range(len(a)):
            v.append(a[i] + b[i])
        return Vec().fromlist(v)

    def __sub__(a, b):
        # Element-wise subtraction
        v = []
        for i in range(len(a)):
            v.append(a[i] - b[i])
        return Vec().fromlist(v)

    def __mul__(self, scalar):
        # Multiply by scalar
        v = []
        for i in range(len(self.v)):
            v.append(self.v[i]*scalar)
        return Vec().fromlist(v)



def test():
    a = vec(1, 2, 3)
    b = vec(3, 2, 1)
    print a
    print b
    print a+b
    print a*3.0

test()