CODEWITHSUNDEEP
pythoninheritanceparent-childsuperclasssuper
Thyrst
Thyrst

Reputation: 2568

Call a parent class method from a child class in Python 2

I want to call parent class method using super() in Python 2.

In Python 3, I'd code it like this:

    class base:
        @classmethod    
        def func(cls):
            print("in base: " + cls.__name__)

    class child(base):
        @classmethod    
        def func(cls):
            super().func()
            print("in child: " + cls.__name__)

    child.func()

with this output:

    in base: child
    in child: child

However, I have no idea, how do this in Python 2. Of course, I can use base.func(), but I don't like to specify parent class name in addition and mainly I get unwanted result:

    in base: base
    in child: child

With cls (cls is child) as first argument in super() function call, I get this error:

    TypeError: must be type, not classobj

Any idea how do it using super() or analogous function in which I don't have to specify name of parent class?

Upvotes: 2

Views: 3781

Answers (3)

echappy
echappy

Reputation: 543

I was trying to do something similar where I was trying to basically "walk up" the inheritance chain until I found a certain base class and then do something there with the class name. The issue I was having was that ALL of these answers assume that you know the name of the class you are trying to get the super of. I tried the "super(cls, cls)" approach but got the "inifinite recursion" issue described above. Here is where I landed

@classmethod
def parent_name(cls):
    if BaseDocument in cls.__bases__:
        # This will return the name of the first parent that subclasses BaseDocument
        return cls.__name__
    else:
        for klass in cls.__bases__:
            try:
                parent_name = klass.parent_name()
                if parent_name is not None:
                    return parent_name
            except AttributeError:
                pass

        return None

Upvotes: 0

Joran Beasley
Joran Beasley

Reputation: 113940

furthering the other answer you can do classmethods for it like

class base(object):
        @classmethod    
        def func(cls):
            print("in base: " + cls.__name__)

class child(base):
        @classmethod    
        def func(cls):
            super(cls, cls).func() 
            print("in child: " + cls.__name__)

child.func()

Upvotes: 4

Tyler McAtee
Tyler McAtee

Reputation: 300

You parent object needs to inherit from object in python 2. So:

class base(object): 
    def func(self):
        print("in base")

class child(base):
    def func(self):
        super(child, self).func()
        print("in child")

c = child()
c.func()

Upvotes: 1

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