python For loop for class attributes?

Question

Is there a way i can loop a function with an argument in a class if that argument is not equal to None? I know how to do this with a lot of if loops, but is there another way I can do this?

Here's an example of what I want to do:

class Name:
    def __init__(self,name,favfood,favcolour,favsport):
        self.name = name
        self.favfood = favfood
        self.favcolour = favcolour
        self.favsport = favsport

henry = Name("Henry","Sushi","Blue",None)

I want a function that prints out all his favourite things, but will skip it if it is None, a for loop for classes pretty much.

Is there a way to have a forloop for every attribute in a class?

https://stackoverflow.com/questions/6886493/get-all-object-attributes-in-python — mbieren
– mbieren, Commented Sep 20, 2018 at 13:35

blhsing · Accepted Answer · 2018-09-20 13:41:16Z

1

You can use the __dict__ attribute of the self object:

class Name:
    def __init__(self,name,favfood,favcolour,favsport):
        self.name = name
        self.favfood = favfood
        self.favcolour = favcolour
        self.favsport = favsport
        for key, value in self.__dict__.items():
            if value is not None:
                print('%s: %s' % (key, value))

henry = Name("Henry","Sushi","Blue",None)

This outputs:

name: Henry
favfood: Sushi
favcolour: Blue

answered Sep 20, 2018 at 13:41

blhsing

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2 Comments

istupidguy Over a year ago

is there a way to use the key variable as an attribute? For example, i can call the attribute with henry.key

Serge Ballesta Over a year ago

The only problem is that not all objects have a __dict__ attribute... When a class defines a __slots__ attribute, its objects have no __dict__.

vash_the_stampede · Accepted Answer · 2018-09-20 14:50:28Z

0

*Updated Would use the __dict__ attribute as @blhsing suggested

class Name:
    def __init__(self,name,favfood,favcolour,favsport):
        self.name = name
        self.favfood = favfood
        self.favcolour = favcolour
        self.favsport = favsport

    def print_favs(self):
        '''even better using @blh method'''
        [print(f'{k}: {v}') for k, v in self.__dict__.items() if v != None]



henry = Name("Henry","Sushi","Blue",None)
henry.print_favs()

(xenial)vash@localhost:~/python/stack_overflow$ python3.7 helping.py 
name: Henry
favfood: Sushi
favcolour: Blue

edited Sep 20, 2018 at 14:50

answered Sep 20, 2018 at 14:44

vash_the_stampede

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1 Comment

Serge Ballesta Over a year ago

Don't. self.lista contains the original values of the attributes. If an attribute receives a new value, self.lista will remain unchanged.

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