Python子类，其属性少于父级

Question

I'm a bit confused here. In two different scripts I've created a child class that has fewer attributes than its parent class. For some reason in one case the code works without issues and in the other I constantly get TypeErrors for missing positional arguments.

This code works without any issues:

class Restaurant:
    def __init__(self, restaurant_name, cuisine_type):
        self.name = restaurant_name
        self.cuisine = cuisine_type
        self.number_served = 0

--SNIP--

class IceCreamStand(Restaurant):
    def __init__(self, restaurant_name):
        super().__init__(self,restaurant_name)
        self.name = restaurant_name

but this, which looks identical to me, constantly fails for some in the line super().__init__(self, first_name) saying that init is missing 2 additional positional arguments.

class User:
    def __init__(self, first_name, last_name, location, occupation):
        self.name = first_name
        self.surname = last_name
        self.location = location
        self.job = occupation
        self.login_attempts = 0

--SNIP--

class Privileges(User):
    def __init__(self, first_name):
        super().__init__(self, first_name)
        self.name = first_name
        self.privileges_admin = ('can add posts'
                           , "can edit other users' posts", 'can delete posts',
                           'can modify posts', 'can ban users')
        self.privileges_user = ('can add posts', 'can edit own posts')

Can anyone please explain why this happens?

Answer 1

When you use super().func()

In my opinion, it mean you call the parent method.

Mean you should pass the same args in parent method.

class User:
    def __init__(self, first_name, last_name, location, occupation):

Like this:

class Privileges(User):
    def __init__(self, first_name):
        super().__init__(first_name, 'default', 'default', 'default')

Or:

class Privileges(User):
    def __init__(self, first_name, last_name, location, occupation):
        super().__init__(first_name, last_name, location, occupation)

I am not very good at english. Hope it will help

Answer 2

You use super().__init__() in wrong way - you have to run it without self .

Restaurant.__init__() expects two values restaurant_name, cuisine_type (not three) and in IceCreamStand.__init__() using super().__init__() you send to Restaurant.__init__() two values self and restaurant_name - but they are assigned in different way that you expect

restaurant = self 
cuisine_type = restaurant_name

If in Restaurant.__init__() you add

print(restaurant_name, cuisine_type)

then you will see your mistake.

---

User.__init__() expects 4 values, not 5 - first_name, last_name, location, occupation . In Privileges.__init__() using super().__init__() you send 2 values to User.__init__() but it needs 2 values more and you get error message "missing 2 additional positional arguments" .