Question

I need to make a variable with similar behaviour like in C lanquage.
I need byte or unsigned char with range 0-255.
This variable should overflow, that means…

myVar = 255
myVar += 1

print myVar #!!myVar = 0!!

Answer 1

I see lots of good answers here. However, if you want to create your own type as you mentioned, you could look at the Python Data model documentation. It explains how to make classes that have customized behaviours, for example emulating numeric types.

With this info, you could make a class like so:

class Num:
    def __init__(self, n):
        self.n = (n % 256)

    def __repr__(self):
        return repr(self.n)

     def __add__(self, other):
        return Num(self.n+int(other))

    # transform ourselves into an int, so
    # int-expecting methods can use us
    def __int__(self):
        return self.n

Then you can do things like this:

>>> a = Num(100)
>>> print a
100
>>> b = a + 50
>>> print b
150
>>> c = Num(200)
>>> d = a + c
>>> print d
44

I realize that you may want to support more operations than I’ve shown in Num, but from this example and the documentation, it should be fairly clear how to add them.