How do I declare an attribute in Python without a value?

Question

In C# I would go:

string UserName; string Password; 

But now, in Python:

class User:     UserName     Password 

I receive an error that UserName isn't defined. Can I not declare a variable without a variable?

Answer 1

In Python, and many other languages, there is a value that means "no value". In Python, that value is None. So you could do something like this:

class User:    username = None    password = None 

Those sure sound like instance variables though, and not class variables, so maybe do this:

class User(object):     def __init__(self):         self.username = None         self.password = None 

Note how Python assigns the None value implicitly from time to time:

def f():     pass g = f() # g now has the value of None