mythicalprogrammer mythicalprogrammer - 1 year ago 59
Python Question

Class with Object as a parameter

I'm trying to translate some python code to scala code. So I'm a total noob in Python.

But why do some classes have object as a parameter but never explicitly use it? What's the reasoning for having it as a parameter in the first place?


class Table(object)

Thank you for your time.

Answer Source

In Python2 this declares Table to be a new-style class (as opposed to "classic" class). In Python3 all classes are new-style classes, so this is no longer necessary.

New style classes have a few special attributes that classic classes lack.

class Classic: pass
class NewStyle(object): pass

# ['__doc__', '__module__']

# ['__class__', '__delattr__', '__dict__', '__doc__', '__format__', '__getattribute__', '__hash__', '__init__', '__module__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__', '__weakref__']

Also, properties and super do not work with classic classes.

In Python2 it is a good idea to make all classes new-style classes. (Though a lot of classes in the standard library are still classic classes, for the sake of backward-compatibility.)

In general, in a statement such as

class Foo(Base1, Base2):

Foo is being declared as a class inheriting from base classes Base1 and Base2.

object is the mother of all classes in Python. It is a new-style class, so inheriting from object makes Table a new-style class.

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