TypeError: super() takes at least 1 argument (0 given) error is specific to any python version?

Question

I'm getting this error

TypeError: super() takes at least 1 argument (0 given)

using this code on python2.7.11:

class Foo(object):
    def __init__(self):
        pass

class Bar(Foo):
    def __init__(self):
        super().__init__()

Bar()

The workaround to make it work would be:

class Foo(object):
    def __init__(self):
        pass

class Bar(Foo):
    def __init__(self):
        super(Bar, self).__init__()

Bar()

It seems the syntax is specific to python 3. So, what's the best way to provide compatible code between 2.x and 3.x and avoiding this error happening?

Solution 1

Yes, the 0-argument syntax is specific to Python 3, see What's New in Python 3.0 and PEP 3135 -- New Super.

In Python 2 and code that must be cross-version compatible, just stick to passing in the class object and instance explicitly.

Yes, there are "backports" available that make a no-argument version of super() work in Python 2 (like the future library) but these require a number of hacks that include a full scan of the class hierarchy to find a matching function object. This is both fragile and slow, and simply not worth the "convenience".

Solution 2

This is because of version of python. Check your python version with [python --version] it might be 2.7

In 2.7 use this [ super(baseclass, self).__init__() ]

---

class Bird(object):
    def __init__(self):
        print("Bird")

    def whatIsThis(self):
        print("This is bird which can not swim")

class Animal(Bird):
    def __init__(self):
        super(Bird,self).__init__()
        print("Animal")

    def whatIsThis(self):
        print("THis is animal which can swim")

a1 = Animal()
a1.whatIsThis()

---

> In 3.0 or more use this [ super().__init__()]

---

class Bird(object):
    def __init__(self):
        print("Bird")

    def whatIsThis(self):
        print("This is bird which can not swim")

class Animal(Bird):
    def __init__(self):
        super().__init__()
        print("Animal")

    def whatIsThis(self):
        print("THis is animal which can swim")

a1 = Animal()
a1.whatIsThis()

Solution 3

You can use the future library to have a Python2/Python3 compatibility.

The super function is back-ported.

Comments

[Martijn Pieters]

Oh boy, but that implementation. Stack frame inspection and a full traverse of the namespaces of the MRO to find the context? I can't recommend actually using this.

[Martijn Pieters]

Just use super(ClassName, self) and repeat yourself a little.

[Mark Bolster]

Why would you make Bird a subclass of animal in an otherwise reasonable answer?

[Solomon Ucko]

@MarkBolster How is that unreasonable?

[Gary02127]

@SolomonUcko - I think he meant why make Animal a subclass of Bird instead of making Bird a subclass of Animal... The latter is more logical.

[Viraj Wadate]

@all this is just dummy example. But still I appreciate your suggestion.