[Tutor] Class: property? function list?

[Sean 'Shaleh' Perry]

On 01-Oct-2001 Run-Sun Pan wrote:
> Dear all,
> 
> [1] --- "property" in class ???
> 
> Is there any "property" in class? For example,
> 
> mc = myclass()
> mc.hitcount = 100  #<===== user input 
> x = mc.hitcount
> print x
> 
> In the above example there's no validation 
> whatsoever. As long as the 100 is passed to
> .hitcount, no matter it's a string or even 
> other object type, it will be past to x. 
> 
> I want to have this .hitcount value validated
> before it is returned to other variable x. In
> some other object-oriented languages you can
> define "properties" for a class for this purpose.
> Is there such device in python ?
> 

The best I have seen done is to define __setattr__ and __getattr__.

def __setattr__(self, name, vale):
        if name == 'hitcount':
                if value < 0 or value > 1000:
                        value = 0
                self.dict['hitcount'] = value

def __getattr__(self, name):
        return self.dict[name]

and in __init__() you just initialize dict and any variables you maintain.