python oop class attribute returns None when set

I’m trying to learn object orientated programming and when setting an attribute why does it return None?

Any tips on writing better code also appreciated… This is my class:

BEANS = ["black", "pinto"]
RICES = ["brown", "white"]
MEATS = ["chicken", "pork", "steak", "tofu"]


class Burrito:

    def __init__(self,
                meat,
                to_go,
                rice,
                beans,
                extra_meat=False,
                guacamole=False,
                cheese=False,
                pico=False,
                corn=False
                ):

        self.meat = self.setter("meat",meat)
        self.rice = self.setter("rice",rice)
        self.beans = self.setter("beans",beans)
        self.to_go = False
        self.extra_meat = False
        self.guacamole = False
        self.cheese = False
        self.pico = False
        self.corn = False

    def setter(self,category,attribute):

        print("category: ",category)
        print("attribute: ",attribute)

        if category == "meat":
            
            if attribute in MEATS:
                self.meat = attribute
            else:
                self.meat = False

        if category == "rice":
            
            if attribute in RICES:
                self.rice = attribute
            else:
                self.rice = False

        if category == "beans":
            
            if attribute in BEANS:
                self.beans = attribute

            else:
                self.beans = False
                
        else:
            self.category = "Error"

When I run this I expected the print to be False but returning None

noodle_burrito = Burrito("spagetti", True, True, False)
print("noodle_burrito.meat: ",noodle_burrito.meat)

And when I run this I expected the print to be tofu but returning None

vegg_burrito = Burrito("tofu", True, True, False)
print("vegg_burrito.meat: ",vegg_burrito.meat)

Thanks for any learning tips! Trying to reference this other SO post but I have never used super before.

>Solution :

Any function that doesn’t explicitly return anything implicitly returns None.

Your setter function internally sets things, but has no other return statement, so

self.meat = self.setter("meat",meat)

ends up setting self.meat to None right after self.setter has already set it to something.

You’re also not doing anything with more than half of the parameters your constructor accepts. I would write your class as

BEANS = {"black", "pinto"}
RICES = {"brown", "white"}
MEATS = {"chicken", "pork", "steak", "tofu"}


def validate_attr(value, options):
    if value in options:
        return value
    return False


class Burrito:
    def __init__(
        self,
        *,
        meat,
        rice,
        beans,
        to_go,
        extra_meat=False,
        guacamole=False,
        cheese=False,
        pico=False,
        corn=False,
    ):
        self.meat = validate_attr(meat, MEATS)
        self.rice = validate_attr(rice, RICES)
        self.beans = validate_attr(beans, BEANS)
        self.to_go = bool(to_go)
        self.extra_meat = bool(extra_meat)
        self.guacamole = bool(guacamole)
        self.cheese = bool(cheese)
        self.pico = bool(pico)
        self.corn = bool(corn)