struct

struct.py

def __make_init(*argnames):
  def __init__(self, *args):
    expected = len(argnames)
    actual = len(args)
    if expected != actual:
      s = '' if expected == 1 else 's'
      raise TypeError("__init__() takes exactly {expected} argument{s} ({actual} given)".format(**locals()))
    for (arg, argname) in zip(args, argnames):
      setattr(self, argname, arg)
  return __init__

def __make_str(name, *argnames):
  def __str__(self):
    arguments = ('{}={}'.format(argname, getattr(self, argname)) for argname in argnames)
    return '{}({})'.format(name, ', '.join(arguments))
  return __str__

def struct(name, *args):
  setattr(__import__('sys').modules[__name__], name, type(name, (), {'__init__' : __make_init(*args), '__str__' : __make_str(name, *args)}))

test_struct.py

from struct import struct

struct('Point2D', 'x', 'y')
struct('Point3D', 'x', 'y', 'z')

p1 = Point2D(1, 2)
p2 = Point2D(3, 4)
p3 = Point3D(1, 2, 3)

print(p1)
print(p2)
print(p3)