inheritance in python 2.7.x

Question

I did this code:

class Square(Quad):
 def __init__(self, linesValue):
 """Calls the builder in quad (same)"""
 super(Square, self).__init__(linesValue)

then It said I have to send type as first arg, so I did this:

class Square(Quad):
 def __init__(self, linesValue):
 """Calls the builder in quad (same)"""
 super(type(Square), self).__init__(linesValue)

then it said obj must be instance of subinstance of class, and as you can see Square(Quad) it is.

• akaIDIOT: Not sure it will solve your issue, but the call to super should be in __init__ (it's currently at the scope of the function definition).
• Ashwini Chaudhary: How did you define Quad? It should inherit from object.

Answer 1

Considering your indentation is correct then in Python2 a class should inherit from object, otherwise it would be considered as a classic class. And you can't use super on a classic class.

So, if Quad is defined like this, then it is wrong:

class Quad:
 def __init__(self, x):
 pass

And instantiating Square will raise error like this:

>>> Square(12)
 ...
 super(Square, self).__init__(linesValue)
TypeError: must be type, not classobj

Change Quad to inherit from object:

class Quad(object):
 def __init__(self, x):
 print x

Demo:

>>> Square(12)
12
<__main__.Square object at 0x93e286c>

• latheiere: There are lot of ways to get error, and OP seems to used all of them consecutively
• Ashwini Chaudhary: @latheiere Unless OP provides exact code and traceback all we can do is guess. ;-)
• user2410243: Thank you! I didn't know that I HAS to be from object

Answer 2

You have bad indentation, and so your super is outside of __init__. Compare:

>>> class Square(Quad):
... def __init__(self, linesValue):
... """Calls the builder in quad (same)"""
... super(Square, self).__init__(linesValue)
...
>>>

and

>>> class Square(Quad):
... def __init__(self, linesValue):
... """Calls the builder in quad (same)"""
... super(type(Square), self).__init__(linesValue)
...
Traceback (most recent call last):
 ...
TypeError: super(type, obj): obj must be an instance or subtype of type

and

>>> class Square(Quad):
... def __init__(self, linesValue):
... """Calls the builder in quad (same)"""
... super(Square, self).__init__(linesValue)
...
Traceback (most recent call last):
 ...
TypeError: super(type, obj): obj must be an instance or subtype of type

• latheiere: There are lot of ways to get error, and OP seems to used all of them consecutively
• user2410243: And the super outside the init was a problem in stackoverflow's topic maker, fixed it