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8.15. types — Names for built-in types

This module defines names for some object types that are used by the standard Python interpreter, but not for the types defined by various extension modules. Also, it does not include some of the types that arise during processing such as the listiterator type. It is safe to use from types import * — the module does not export any names besides the ones listed here. New names exported by future versions of this module will all end in Type.

Typical use is for functions that do different things depending on their argument types, like the following:

from types import * def delete(mylist, item):

if type(item) is IntType:
del mylist[item]

Starting in Python 2.2, built-in factory functions such as int() and str() are also names for the corresponding types. This is now the preferred way to access the type instead of using the types module. Accordingly, the example above should be written as follows:

def delete(mylist, item):
if isinstance(item, int):
del mylist[item]

The module defines the following names:


The type of None.


The type of type objects (such as returned by type()); alias of the built-in type.


The type of the bool values True and False; alias of the built-in bool.

New in version 2.3.


The type of integers (e.g. 1); alias of the built-in int.


The type of long integers (e.g. 1L); alias of the built-in long.


The type of floating point numbers (e.g. 1.0); alias of the built-in float.


The type of complex numbers (e.g. 1.0j). This is not defined if Python was built without complex number support.


The type of character strings (e.g. 'Spam'); alias of the built-in str.


The type of Unicode character strings (e.g. u'Spam'). This is not defined if Python was built without Unicode support. It’s an alias of the built-in unicode.


The type of tuples (e.g. (1, 2, 3, 'Spam')); alias of the built-in tuple.


The type of lists (e.g. [0, 1, 2, 3]); alias of the built-in list.


The type of dictionaries (e.g. {'Bacon': 1, 'Ham': 0}); alias of the built-in dict.


An alternate name for DictType.

types.FunctionType types.LambdaType

The type of user-defined functions and functions created by lambda expressions.


The type of generator-iterator objects, produced by calling a generator function.

New in version 2.2.


The type for code objects such as returned by compile().


The type of user-defined old-style classes.


The type of instances of user-defined classes.


The type of methods of user-defined class instances.


An alternate name for MethodType.

types.BuiltinFunctionType types.BuiltinMethodType

The type of built-in functions like len() or sys.exit(), and methods of built-in classes. (Here, the term “built-in” means “written in C”.)


The type of modules.


The type of open file objects such as sys.stdout; alias of the built-in file.


The type of range objects returned by xrange(); alias of the built-in xrange.


The type of objects returned by slice(); alias of the built-in slice.


The type of Ellipsis.


The type of traceback objects such as found in sys.exc_traceback.


The type of frame objects such as found in tb.tb_frame if tb is a traceback object.


The type of buffer objects created by the buffer() function.


The type of dict proxies, such as TypeType.__dict__.


The type of NotImplemented


The type of objects defined in extension modules with PyGetSetDef, such as FrameType.f_locals or array.array.typecode. This type is used as descriptor for object attributes; it has the same purpose as the property type, but for classes defined in extension modules.

New in version 2.5.


The type of objects defined in extension modules with PyMemberDef, such as datetime.timedelta.days. This type is used as descriptor for simple C data members which use standard conversion functions; it has the same purpose as the property type, but for classes defined in extension modules. In other implementations of Python, this type may be identical to GetSetDescriptorType.

New in version 2.5.


A sequence containing StringType and UnicodeType used to facilitate easier checking for any string object. Using this is more portable than using a sequence of the two string types constructed elsewhere since it only contains UnicodeType if it has been built in the running version of Python. For example: isinstance(s, types.StringTypes).

New in version 2.2.