Metaclasses are for when your class needs to behave differently from a normal class or when you want to alter the behavior of the class
statement. Neither of those apply here, so there's really no need to use a metaclass. In fact, you could just have one ModularInteger
class with instances that record their value and modulus, but assuming you don't want to do that, it's still easy to do this with an ordinary class statement:
def integers_mod_p(p):
class IntegerModP(object):
def __init__(self, n):
self.n = n % IntegerModP.p
def typecheck(self, other):
try:
if self.p != other.p:
raise TypeError
except AttributeError:
raise TypeError
def __add__(self, other):
self.typecheck(other)
return IntegerModP(self.n + other.n)
def __sub__(self, other):
...
IntegerModP.p = p
IntegerModP.__name__ = 'IntegerMod{}'.format(p)
return IntegerModP