Steven D'Aprano wrote:
I have a subclass of int where I want all the standard arithmetic
operators to return my subclass, but with no other differences:
class MyInt(int):
def __add__(self, other):
return self.__class__(super(MyInt, self).__add__(other))
# and so on for __mul__, __sub__, etc.
Just an idea:
def myint(meth):
def mymeth(*args):
return MyInt(meth(*args))
return mymeth
class MyIntMeta(type):
method_names = 'add sub mul neg'.split()
def __new__(cls, name, bases, attrs):
t = type.__new__(cls, name, bases, attrs)
for name in MyIntMeta.method_names:
name = '__%s__' % name
meth = getattr(t, name)
setattr(t, name, myint(meth))
return t
class MyInt(int):
__metaclass__ = MyIntMeta
a = MyInt(3)
b = MyInt(3000)
print a
print b
c = a + b
print c
assert isinstance(c, MyInt)
d = c * MyInt(4)
print d
e = c * 6 * a * b
print e
assert isinstance(e, MyInt)
x = -e
print x
assert isinstance(x, MyInt)
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