CODEWITHSUNDEEP
python
Mike
Mike

Reputation: 60743

What is 'type' in Python?

>>> type(type)
<type 'type'>

I expect the type of type to be a function since it's used to return the type of the argument. Does this mean a type can accept arguments? Is type something unusual/special?

Upvotes: 2

Views: 175

Answers (4)

kindall
kindall

Reputation: 184071

Classes are objects. All objects are instances of a class. So since a class is an object, it is an instance of some class. The class that a class is an instance of is named type. It is the base metaclass.

Originally type() was just a function that returned an object's class. In Python 2.2, user-defined classes and built-in types were unified, and type became a class. For backward compatibility, it still behaves like the old type() function when called with one argument.

Upvotes: 4

lvc
lvc

Reputation: 35059

type is a metaclass: a class whose instances are also classes. The type of any other builtin class will also be type - eg:

>>> type(object)
<class 'type'>
>>> type(list)
<class 'type'>

Indeed, every (new-style) class will also be an instance of type, although if it is defined with a custom metaclass, type(my_class) will be that metaclass. But since every metaclass is required to inherit from type, you will have, for any class:

>>> isinstance(my_class, type)
True

Upvotes: 5

Anand S Kumar
Anand S Kumar

Reputation: 90859

As can be clearly seen in the documentations -

class type(object)
class type(name, bases, dict)

With one argument, return the type of an object. The return value is a type object. The isinstance() built-in function is recommended for testing the type of an object.

type is a class, not a function.

Upvotes: 1

Ignacio Vazquez-Abrams
Ignacio Vazquez-Abrams

Reputation: 798436

type is Python's class ur-type. When called with a single argument it returns the type of the argument. When called with 3 arguments it returns a class whose characteristics are determined by the arguments.

Upvotes: 1

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