relationship between type (metaclass) and object (superclass)

Question

I have a basic understanding of python. Can anybody tell me what is the relation between 'type' and 'object' (I know that type is sub-class of object). Because when we execute the following statements in interpreter, the output is confusing about their relationship with each other i.e. how they resolve this confusion.

1)

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

By seeing the above result we can say that type of 'object' is 'type', and type of 'type' is also 'type'.

2) The same result as above can be achieved by this also.

type.__class__
<type 'type'>
>>> object.__class__
<type 'type'>

And by observing this we can say that class object is of type 'type' and class 'type' is type of itself. 3)

object.__bases__
()
>>> type.__bases__
(<type 'object'>,)

But when I go for superclasses of each, I found that object is superclass of all classes in New-style class system, while type is subclass of object.

I only want to know the relationship between these two classes. How they are connected to each other. Can anybody suggest me any good study material to get into python internals.

[This](http://stackoverflow.com/a/6581949/198633) is related and of interest, though perhaps a bit advanced — inspectorG4dget, Jul 19 '13 at 05:55

score 2 · Answer 1 · answered Jul 19 '13 at 05:44

2

The relationship is that type is a subclass of object. Additionally, type(x) where x is any type (including both type itself and object) returns type:

>>> type(int)
<type 'type'>
>>> type(str)
<type 'type'>
>>> type(object)
<type 'type'>
>>> type(type)
<type 'type'>

However:

>>> type(0)
<type 'int'>
>>> type('')
<type 'str'>

answered Jul 19 '13 at 05:44

NPE

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I know that type is subclass of object. but if object is superclass of type then how type of 'object' is 'type', and type of 'type' is 'type'. – tailor_raj Jul 19 '13 at 06:04
@tailor_raj: As I (unsuccessfully) tried to explain, the `type()` of *any class* is `type`. – NPE Jul 19 '13 at 06:08

score 2 · Answer 2 · answered Jul 19 '13 at 07:19

object and type are both instances of type. type is a subclass of object.

This is a bit strange, and not something you could replicate with your own user-defined classes. However, it makes sense if you think about what type and object are:

list is a type, and everything is an object. Thus, type and object are kinds of things, a.k.a. instances of type.

Everything is an object. In particular, types are objects too. Thus, type is a subclass of object.

relationship between type (metaclass) and object (superclass)

2 Answers2