A newbie question about class

[Fernando Pérez]

newgene wrote:

> Hi, group,
>      I have a newbie question about building a class:
> 
> eg.
> 
> class A:
>    def __init__(self,x=None):
>        self.x=x
>        if self.x != None:
>             self.y=x**2
>        else:
>             self.y=x**2

This code has a problem: None**2 gives a TypeError exception.

f