Python Documentation contents¶
- What’s New in Python
- What’s New In Python 3.11
- Summary – Release highlights
- New Features
- New Features Related to Type Hints
- Other Language Changes
- Other CPython Implementation Changes
- New Modules
- Improved Modules
- Optimizations
- Faster CPython
- CPython bytecode changes
- Deprecated
- Pending Removal in Python 3.12
- Removed
- Porting to Python 3.11
- Build Changes
- C API Changes
- What’s New In Python 3.10
- Summary – Release highlights
- New Features
- New Features Related to Type Hints
- Other Language Changes
- New Modules
- Improved Modules
- asyncio
- argparse
- array
- asynchat, asyncore, smtpd
- base64
- bdb
- bisect
- codecs
- collections.abc
- contextlib
- curses
- dataclasses
- distutils
- doctest
- encodings
- enum
- fileinput
- faulthandler
- gc
- glob
- hashlib
- hmac
- IDLE and idlelib
- importlib.metadata
- inspect
- itertools
- linecache
- os
- os.path
- pathlib
- platform
- pprint
- py_compile
- pyclbr
- shelve
- statistics
- site
- socket
- ssl
- sqlite3
- sys
- _thread
- threading
- traceback
- types
- typing
- unittest
- urllib.parse
- xml
- zipimport
- Optimizations
- Deprecated
- Removed
- Porting to Python 3.10
- CPython bytecode changes
- Build Changes
- C API Changes
- What’s New In Python 3.9
- What’s New In Python 3.8
- Summary – Release highlights
- New Features
- Assignment expressions
- Positional-only parameters
- Parallel filesystem cache for compiled bytecode files
- Debug build uses the same ABI as release build
- f-strings support
=for self-documenting expressions and debugging - PEP 578: Python Runtime Audit Hooks
- PEP 587: Python Initialization Configuration
- PEP 590: Vectorcall: a fast calling protocol for CPython
- Pickle protocol 5 with out-of-band data buffers
- Other Language Changes
- New Modules
- Improved Modules
- ast
- asyncio
- builtins
- collections
- cProfile
- csv
- curses
- ctypes
- datetime
- functools
- gc
- gettext
- gzip
- IDLE and idlelib
- inspect
- io
- itertools
- json.tool
- logging
- math
- mmap
- multiprocessing
- os
- os.path
- pathlib
- pickle
- plistlib
- pprint
- py_compile
- shlex
- shutil
- socket
- ssl
- statistics
- sys
- tarfile
- threading
- tokenize
- tkinter
- time
- typing
- unicodedata
- unittest
- venv
- weakref
- xml
- xmlrpc
- Optimizations
- Build and C API Changes
- Deprecated
- API and Feature Removals
- Porting to Python 3.8
- Notable changes in Python 3.8.1
- Notable changes in Python 3.8.8
- Notable changes in Python 3.8.12
- What’s New In Python 3.7
- Summary – Release Highlights
- New Features
- PEP 563: Postponed Evaluation of Annotations
- PEP 538: Legacy C Locale Coercion
- PEP 540: Forced UTF-8 Runtime Mode
- PEP 553: Built-in
breakpoint() - PEP 539: New C API for Thread-Local Storage
- PEP 562: Customization of Access to Module Attributes
- PEP 564: New Time Functions With Nanosecond Resolution
- PEP 565: Show DeprecationWarning in
__main__ - PEP 560: Core Support for
typingmodule and Generic Types - PEP 552: Hash-based .pyc Files
- PEP 545: Python Documentation Translations
- Python Development Mode (-X dev)
- Other Language Changes
- New Modules
- Improved Modules
- argparse
- asyncio
- binascii
- calendar
- collections
- compileall
- concurrent.futures
- contextlib
- cProfile
- crypt
- datetime
- dbm
- decimal
- dis
- distutils
- enum
- functools
- gc
- hmac
- http.client
- http.server
- idlelib and IDLE
- importlib
- io
- ipaddress
- itertools
- locale
- logging
- math
- mimetypes
- msilib
- multiprocessing
- os
- pathlib
- pdb
- py_compile
- pydoc
- queue
- re
- signal
- socket
- socketserver
- sqlite3
- ssl
- string
- subprocess
- sys
- time
- tkinter
- tracemalloc
- types
- unicodedata
- unittest
- unittest.mock
- urllib.parse
- uu
- uuid
- warnings
- xml.etree
- xmlrpc.server
- zipapp
- zipfile
- C API Changes
- Build Changes
- Optimizations
- Other CPython Implementation Changes
- Deprecated Python Behavior
- Deprecated Python modules, functions and methods
- Deprecated functions and types of the C API
- Platform Support Removals
- API and Feature Removals
- Module Removals
- Windows-only Changes
- Porting to Python 3.7
- Notable changes in Python 3.7.1
- Notable changes in Python 3.7.2
- Notable changes in Python 3.7.6
- Notable changes in Python 3.7.10
- What’s New In Python 3.6
- Summary – Release highlights
- New Features
- PEP 498: Formatted string literals
- PEP 526: Syntax for variable annotations
- PEP 515: Underscores in Numeric Literals
- PEP 525: Asynchronous Generators
- PEP 530: Asynchronous Comprehensions
- PEP 487: Simpler customization of class creation
- PEP 487: Descriptor Protocol Enhancements
- PEP 519: Adding a file system path protocol
- PEP 495: Local Time Disambiguation
- PEP 529: Change Windows filesystem encoding to UTF-8
- PEP 528: Change Windows console encoding to UTF-8
- PEP 520: Preserving Class Attribute Definition Order
- PEP 468: Preserving Keyword Argument Order
- New dict implementation
- PEP 523: Adding a frame evaluation API to CPython
- PYTHONMALLOC environment variable
- DTrace and SystemTap probing support
- Other Language Changes
- New Modules
- Improved Modules
- array
- ast
- asyncio
- binascii
- cmath
- collections
- concurrent.futures
- contextlib
- datetime
- decimal
- distutils
- encodings
- enum
- faulthandler
- fileinput
- hashlib
- http.client
- idlelib and IDLE
- importlib
- inspect
- json
- logging
- math
- multiprocessing
- os
- pathlib
- pdb
- pickle
- pickletools
- pydoc
- random
- re
- readline
- rlcompleter
- shlex
- site
- sqlite3
- socket
- socketserver
- ssl
- statistics
- struct
- subprocess
- sys
- telnetlib
- time
- timeit
- tkinter
- traceback
- tracemalloc
- typing
- unicodedata
- unittest.mock
- urllib.request
- urllib.robotparser
- venv
- warnings
- winreg
- winsound
- xmlrpc.client
- zipfile
- zlib
- Optimizations
- Build and C API Changes
- Other Improvements
- Deprecated
- Removed
- Porting to Python 3.6
- Notable changes in Python 3.6.2
- Notable changes in Python 3.6.4
- Notable changes in Python 3.6.5
- Notable changes in Python 3.6.7
- Notable changes in Python 3.6.10
- Notable changes in Python 3.6.13
- What’s New In Python 3.5
- Summary – Release highlights
- New Features
- PEP 492 - Coroutines with async and await syntax
- PEP 465 - A dedicated infix operator for matrix multiplication
- PEP 448 - Additional Unpacking Generalizations
- PEP 461 - percent formatting support for bytes and bytearray
- PEP 484 - Type Hints
- PEP 471 - os.scandir() function – a better and faster directory iterator
- PEP 475: Retry system calls failing with EINTR
- PEP 479: Change StopIteration handling inside generators
- PEP 485: A function for testing approximate equality
- PEP 486: Make the Python Launcher aware of virtual environments
- PEP 488: Elimination of PYO files
- PEP 489: Multi-phase extension module initialization
- Other Language Changes
- New Modules
- Improved Modules
- argparse
- asyncio
- bz2
- cgi
- cmath
- code
- collections
- collections.abc
- compileall
- concurrent.futures
- configparser
- contextlib
- csv
- curses
- dbm
- difflib
- distutils
- doctest
- enum
- faulthandler
- functools
- glob
- gzip
- heapq
- http
- http.client
- idlelib and IDLE
- imaplib
- imghdr
- importlib
- inspect
- io
- ipaddress
- json
- linecache
- locale
- logging
- lzma
- math
- multiprocessing
- operator
- os
- pathlib
- pickle
- poplib
- re
- readline
- selectors
- shutil
- signal
- smtpd
- smtplib
- sndhdr
- socket
- ssl
- sqlite3
- subprocess
- sys
- sysconfig
- tarfile
- threading
- time
- timeit
- tkinter
- traceback
- types
- unicodedata
- unittest
- unittest.mock
- urllib
- wsgiref
- xmlrpc
- xml.sax
- zipfile
- Other module-level changes
- Optimizations
- Build and C API Changes
- Deprecated
- Removed
- Porting to Python 3.5
- Notable changes in Python 3.5.4
- What’s New In Python 3.4
- Summary – Release Highlights
- New Features
- New Modules
- Improved Modules
- abc
- aifc
- argparse
- audioop
- base64
- collections
- colorsys
- contextlib
- dbm
- dis
- doctest
- filecmp
- functools
- gc
- glob
- hashlib
- hmac
- html
- http
- idlelib and IDLE
- importlib
- inspect
- ipaddress
- logging
- marshal
- mmap
- multiprocessing
- operator
- os
- pdb
- pickle
- plistlib
- poplib
- pprint
- pty
- pydoc
- re
- resource
- select
- shelve
- shutil
- smtpd
- smtplib
- socket
- sqlite3
- ssl
- stat
- struct
- subprocess
- sunau
- sys
- tarfile
- textwrap
- threading
- traceback
- types
- urllib
- unittest
- venv
- wave
- weakref
- xml.etree
- zipfile
- CPython Implementation Changes
- Deprecated
- Removed
- Porting to Python 3.4
- Changed in 3.4.3
- What’s New In Python 3.3
- Summary – Release highlights
- PEP 405: Virtual Environments
- PEP 420: Implicit Namespace Packages
- PEP 3118: New memoryview implementation and buffer protocol documentation
- PEP 393: Flexible String Representation
- PEP 397: Python Launcher for Windows
- PEP 3151: Reworking the OS and IO exception hierarchy
- PEP 380: Syntax for Delegating to a Subgenerator
- PEP 409: Suppressing exception context
- PEP 414: Explicit Unicode literals
- PEP 3155: Qualified name for classes and functions
- PEP 412: Key-Sharing Dictionary
- PEP 362: Function Signature Object
- PEP 421: Adding sys.implementation
- Using importlib as the Implementation of Import
- Other Language Changes
- A Finer-Grained Import Lock
- Builtin functions and types
- New Modules
- Improved Modules
- abc
- array
- base64
- binascii
- bz2
- codecs
- collections
- contextlib
- crypt
- curses
- datetime
- decimal
- ftplib
- functools
- gc
- hmac
- http
- html
- imaplib
- inspect
- io
- itertools
- logging
- math
- mmap
- multiprocessing
- nntplib
- os
- pdb
- pickle
- pydoc
- re
- sched
- select
- shlex
- shutil
- signal
- smtpd
- smtplib
- socket
- socketserver
- sqlite3
- ssl
- stat
- struct
- subprocess
- sys
- tarfile
- tempfile
- textwrap
- threading
- time
- types
- unittest
- urllib
- webbrowser
- xml.etree.ElementTree
- zlib
- Optimizations
- Build and C API Changes
- Deprecated
- Porting to Python 3.3
- What’s New In Python 3.2
- PEP 384: Defining a Stable ABI
- PEP 389: Argparse Command Line Parsing Module
- PEP 391: Dictionary Based Configuration for Logging
- PEP 3148: The
concurrent.futuresmodule - PEP 3147: PYC Repository Directories
- PEP 3149: ABI Version Tagged .so Files
- PEP 3333: Python Web Server Gateway Interface v1.0.1
- Other Language Changes
- New, Improved, and Deprecated Modules
- elementtree
- functools
- itertools
- collections
- threading
- datetime and time
- math
- abc
- io
- reprlib
- logging
- csv
- contextlib
- decimal and fractions
- ftp
- popen
- select
- gzip and zipfile
- tarfile
- hashlib
- ast
- os
- shutil
- sqlite3
- html
- socket
- ssl
- nntp
- certificates
- imaplib
- http.client
- unittest
- random
- poplib
- asyncore
- tempfile
- inspect
- pydoc
- dis
- dbm
- ctypes
- site
- sysconfig
- pdb
- configparser
- urllib.parse
- mailbox
- turtledemo
- Multi-threading
- Optimizations
- Unicode
- Codecs
- Documentation
- IDLE
- Code Repository
- Build and C API Changes
- Porting to Python 3.2
- What’s New In Python 3.1
- What’s New In Python 3.0
- What’s New in Python 2.7
- The Future for Python 2.x
- Changes to the Handling of Deprecation Warnings
- Python 3.1 Features
- PEP 372: Adding an Ordered Dictionary to collections
- PEP 378: Format Specifier for Thousands Separator
- PEP 389: The argparse Module for Parsing Command Lines
- PEP 391: Dictionary-Based Configuration For Logging
- PEP 3106: Dictionary Views
- PEP 3137: The memoryview Object
- Other Language Changes
- New and Improved Modules
- Build and C API Changes
- Other Changes and Fixes
- Porting to Python 2.7
- New Features Added to Python 2.7 Maintenance Releases
- Two new environment variables for debug mode
- PEP 434: IDLE Enhancement Exception for All Branches
- PEP 466: Network Security Enhancements for Python 2.7
- PEP 477: Backport ensurepip (PEP 453) to Python 2.7
- PEP 476: Enabling certificate verification by default for stdlib http clients
- PEP 493: HTTPS verification migration tools for Python 2.7
- New
make regen-allbuild target - Removal of
make touchbuild target
- Acknowledgements
- What’s New in Python 2.6
- Python 3.0
- Changes to the Development Process
- PEP 343: The ‘with’ statement
- PEP 366: Explicit Relative Imports From a Main Module
- PEP 370: Per-user
site-packagesDirectory - PEP 371: The
multiprocessingPackage - PEP 3101: Advanced String Formatting
- PEP 3105:
printAs a Function - PEP 3110: Exception-Handling Changes
- PEP 3112: Byte Literals
- PEP 3116: New I/O Library
- PEP 3118: Revised Buffer Protocol
- PEP 3119: Abstract Base Classes
- PEP 3127: Integer Literal Support and Syntax
- PEP 3129: Class Decorators
- PEP 3141: A Type Hierarchy for Numbers
- Other Language Changes
- New and Improved Modules
- Deprecations and Removals
- Build and C API Changes
- Porting to Python 2.6
- Acknowledgements
- What’s New in Python 2.5
- PEP 308: Conditional Expressions
- PEP 309: Partial Function Application
- PEP 314: Metadata for Python Software Packages v1.1
- PEP 328: Absolute and Relative Imports
- PEP 338: Executing Modules as Scripts
- PEP 341: Unified try/except/finally
- PEP 342: New Generator Features
- PEP 343: The ‘with’ statement
- PEP 352: Exceptions as New-Style Classes
- PEP 353: Using ssize_t as the index type
- PEP 357: The ‘__index__’ method
- Other Language Changes
- New, Improved, and Removed Modules
- Build and C API Changes
- Porting to Python 2.5
- Acknowledgements
- What’s New in Python 2.4
- PEP 218: Built-In Set Objects
- PEP 237: Unifying Long Integers and Integers
- PEP 289: Generator Expressions
- PEP 292: Simpler String Substitutions
- PEP 318: Decorators for Functions and Methods
- PEP 322: Reverse Iteration
- PEP 324: New subprocess Module
- PEP 327: Decimal Data Type
- PEP 328: Multi-line Imports
- PEP 331: Locale-Independent Float/String Conversions
- Other Language Changes
- New, Improved, and Deprecated Modules
- Build and C API Changes
- Porting to Python 2.4
- Acknowledgements
- What’s New in Python 2.3
- PEP 218: A Standard Set Datatype
- PEP 255: Simple Generators
- PEP 263: Source Code Encodings
- PEP 273: Importing Modules from ZIP Archives
- PEP 277: Unicode file name support for Windows NT
- PEP 278: Universal Newline Support
- PEP 279: enumerate()
- PEP 282: The logging Package
- PEP 285: A Boolean Type
- PEP 293: Codec Error Handling Callbacks
- PEP 301: Package Index and Metadata for Distutils
- PEP 302: New Import Hooks
- PEP 305: Comma-separated Files
- PEP 307: Pickle Enhancements
- Extended Slices
- Other Language Changes
- New, Improved, and Deprecated Modules
- Pymalloc: A Specialized Object Allocator
- Build and C API Changes
- Other Changes and Fixes
- Porting to Python 2.3
- Acknowledgements
- What’s New in Python 2.2
- Introduction
- PEPs 252 and 253: Type and Class Changes
- PEP 234: Iterators
- PEP 255: Simple Generators
- PEP 237: Unifying Long Integers and Integers
- PEP 238: Changing the Division Operator
- Unicode Changes
- PEP 227: Nested Scopes
- New and Improved Modules
- Interpreter Changes and Fixes
- Other Changes and Fixes
- Acknowledgements
- What’s New in Python 2.1
- Introduction
- PEP 227: Nested Scopes
- PEP 236: __future__ Directives
- PEP 207: Rich Comparisons
- PEP 230: Warning Framework
- PEP 229: New Build System
- PEP 205: Weak References
- PEP 232: Function Attributes
- PEP 235: Importing Modules on Case-Insensitive Platforms
- PEP 217: Interactive Display Hook
- PEP 208: New Coercion Model
- PEP 241: Metadata in Python Packages
- New and Improved Modules
- Other Changes and Fixes
- Acknowledgements
- What’s New in Python 2.0
- Introduction
- What About Python 1.6?
- New Development Process
- Unicode
- List Comprehensions
- Augmented Assignment
- String Methods
- Garbage Collection of Cycles
- Other Core Changes
- Porting to 2.0
- Extending/Embedding Changes
- Distutils: Making Modules Easy to Install
- XML Modules
- Module changes
- New modules
- IDLE Improvements
- Deleted and Deprecated Modules
- Acknowledgements
- Changelog
- Python next
- Python 3.11.2 final
- Python 3.11.1 final
- Python 3.11.0 final
- Python 3.11.0 release candidate 2
- Python 3.11.0 release candidate 1
- Python 3.11.0 beta 5
- Python 3.11.0 beta 4
- Python 3.11.0 beta 3
- Python 3.11.0 beta 2
- Python 3.11.0 beta 1
- Python 3.11.0 alpha 7
- Python 3.11.0 alpha 6
- Python 3.11.0 alpha 5
- Python 3.11.0 alpha 4
- Python 3.11.0 alpha 3
- Python 3.11.0 alpha 2
- Python 3.11.0 alpha 1
- Python 3.10.0 beta 1
- Python 3.10.0 alpha 7
- Python 3.10.0 alpha 6
- Python 3.10.0 alpha 5
- Python 3.10.0 alpha 4
- Python 3.10.0 alpha 3
- Python 3.10.0 alpha 2
- Python 3.10.0 alpha 1
- Python 3.9.0 beta 1
- Python 3.9.0 alpha 6
- Python 3.9.0 alpha 5
- Python 3.9.0 alpha 4
- Python 3.9.0 alpha 3
- Python 3.9.0 alpha 2
- Python 3.9.0 alpha 1
- Python 3.8.0 beta 1
- Python 3.8.0 alpha 4
- Python 3.8.0 alpha 3
- Python 3.8.0 alpha 2
- Python 3.8.0 alpha 1
- Python 3.7.0 final
- Python 3.7.0 release candidate 1
- Python 3.7.0 beta 5
- Python 3.7.0 beta 4
- Python 3.7.0 beta 3
- Python 3.7.0 beta 2
- Python 3.7.0 beta 1
- Python 3.7.0 alpha 4
- Python 3.7.0 alpha 3
- Python 3.7.0 alpha 2
- Python 3.7.0 alpha 1
- Python 3.6.6 final
- Python 3.6.6 release candidate 1
- Python 3.6.5 final
- Python 3.6.5 release candidate 1
- Python 3.6.4 final
- Python 3.6.4 release candidate 1
- Python 3.6.3 final
- Python 3.6.3 release candidate 1
- Python 3.6.2 final
- Python 3.6.2 release candidate 2
- Python 3.6.2 release candidate 1
- Python 3.6.1 final
- Python 3.6.1 release candidate 1
- Python 3.6.0 final
- Python 3.6.0 release candidate 2
- Python 3.6.0 release candidate 1
- Python 3.6.0 beta 4
- Python 3.6.0 beta 3
- Python 3.6.0 beta 2
- Python 3.6.0 beta 1
- Python 3.6.0 alpha 4
- Python 3.6.0 alpha 3
- Python 3.6.0 alpha 2
- Python 3.6.0 alpha 1
- Python 3.5.5 final
- Python 3.5.5 release candidate 1
- Python 3.5.4 final
- Python 3.5.4 release candidate 1
- Python 3.5.3 final
- Python 3.5.3 release candidate 1
- Python 3.5.2 final
- Python 3.5.2 release candidate 1
- Python 3.5.1 final
- Python 3.5.1 release candidate 1
- Python 3.5.0 final
- Python 3.5.0 release candidate 4
- Python 3.5.0 release candidate 3
- Python 3.5.0 release candidate 2
- Python 3.5.0 release candidate 1
- Python 3.5.0 beta 4
- Python 3.5.0 beta 3
- Python 3.5.0 beta 2
- Python 3.5.0 beta 1
- Python 3.5.0 alpha 4
- Python 3.5.0 alpha 3
- Python 3.5.0 alpha 2
- Python 3.5.0 alpha 1
- What’s New In Python 3.11
- The Python Tutorial
- 1. Whetting Your Appetite
- 2. Using the Python Interpreter
- 3. An Informal Introduction to Python
- 4. More Control Flow Tools
- 4.1.
ifStatements - 4.2.
forStatements - 4.3. The
range()Function - 4.4.
breakandcontinueStatements, andelseClauses on Loops - 4.5.
passStatements - 4.6.
matchStatements - 4.7. Defining Functions
- 4.8. More on Defining Functions
- 4.9. Intermezzo: Coding Style
- 4.1.
- 5. Data Structures
- 6. Modules
- 7. Input and Output
- 8. Errors and Exceptions
- 9. Classes
- 10. Brief Tour of the Standard Library
- 10.1. Operating System Interface
- 10.2. File Wildcards
- 10.3. Command Line Arguments
- 10.4. Error Output Redirection and Program Termination
- 10.5. String Pattern Matching
- 10.6. Mathematics
- 10.7. Internet Access
- 10.8. Dates and Times
- 10.9. Data Compression
- 10.10. Performance Measurement
- 10.11. Quality Control
- 10.12. Batteries Included
- 11. Brief Tour of the Standard Library — Part II
- 12. Virtual Environments and Packages
- 13. What Now?
- 14. Interactive Input Editing and History Substitution
- 15. Floating Point Arithmetic: Issues and Limitations
- 16. Appendix
- Python Setup and Usage
- 1. Command line and environment
- 2. Using Python on Unix platforms
- 3. Configure Python
- 4. Using Python on Windows
- 4.1. The full installer
- 4.2. The Microsoft Store package
- 4.3. The nuget.org packages
- 4.4. The embeddable package
- 4.5. Alternative bundles
- 4.6. Configuring Python
- 4.7. UTF-8 mode
- 4.8. Python Launcher for Windows
- 4.9. Finding modules
- 4.10. Additional modules
- 4.11. Compiling Python on Windows
- 4.12. Other Platforms
- 5. Using Python on a Mac
- 6. Editors and IDEs
- The Python Language Reference
- 1. Introduction
- 2. Lexical analysis
- 3. Data model
- 3.1. Objects, values and types
- 3.2. The standard type hierarchy
- 3.3. Special method names
- 3.3.1. Basic customization
- 3.3.2. Customizing attribute access
- 3.3.3. Customizing class creation
- 3.3.4. Customizing instance and subclass checks
- 3.3.5. Emulating generic types
- 3.3.6. Emulating callable objects
- 3.3.7. Emulating container types
- 3.3.8. Emulating numeric types
- 3.3.9. With Statement Context Managers
- 3.3.10. Customizing positional arguments in class pattern matching
- 3.3.11. Special method lookup
- 3.4. Coroutines
- 4. Execution model
- 5. The import system
- 6. Expressions
- 6.1. Arithmetic conversions
- 6.2. Atoms
- 6.3. Primaries
- 6.4. Await expression
- 6.5. The power operator
- 6.6. Unary arithmetic and bitwise operations
- 6.7. Binary arithmetic operations
- 6.8. Shifting operations
- 6.9. Binary bitwise operations
- 6.10. Comparisons
- 6.11. Boolean operations
- 6.12. Assignment expressions
- 6.13. Conditional expressions
- 6.14. Lambdas
- 6.15. Expression lists
- 6.16. Evaluation order
- 6.17. Operator precedence
- 7. Simple statements
- 7.1. Expression statements
- 7.2. Assignment statements
- 7.3. The
assertstatement - 7.4. The
passstatement - 7.5. The
delstatement - 7.6. The
returnstatement - 7.7. The
yieldstatement - 7.8. The
raisestatement - 7.9. The
breakstatement - 7.10. The
continuestatement - 7.11. The
importstatement - 7.12. The
globalstatement - 7.13. The
nonlocalstatement
- 8. Compound statements
- 9. Top-level components
- 10. Full Grammar specification
- The Python Standard Library
- Introduction
- Built-in Functions
- Built-in Constants
- Built-in Types
- Truth Value Testing
- Boolean Operations —
and,or,not - Comparisons
- Numeric Types —
int,float,complex - Iterator Types
- Sequence Types —
list,tuple,range - Text Sequence Type —
str - Binary Sequence Types —
bytes,bytearray,memoryview - Set Types —
set,frozenset - Mapping Types —
dict - Context Manager Types
- Type Annotation Types — Generic Alias, Union
- Other Built-in Types
- Special Attributes
- Integer string conversion length limitation
- Built-in Exceptions
- Text Processing Services
string— Common string operationsre— Regular expression operationsdifflib— Helpers for computing deltastextwrap— Text wrapping and fillingunicodedata— Unicode Databasestringprep— Internet String Preparationreadline— GNU readline interfacerlcompleter— Completion function for GNU readline
- Binary Data Services
struct— Interpret bytes as packed binary datacodecs— Codec registry and base classes
- Data Types
datetime— Basic date and time typeszoneinfo— IANA time zone supportcalendar— General calendar-related functionscollections— Container datatypescollections.abc— Abstract Base Classes for Containersheapq— Heap queue algorithmbisect— Array bisection algorithmarray— Efficient arrays of numeric valuesweakref— Weak referencestypes— Dynamic type creation and names for built-in typescopy— Shallow and deep copy operationspprint— Data pretty printerreprlib— Alternaterepr()implementationenum— Support for enumerationsgraphlib— Functionality to operate with graph-like structures
- Numeric and Mathematical Modules
- Functional Programming Modules
- File and Directory Access
pathlib— Object-oriented filesystem pathsos.path— Common pathname manipulationsfileinput— Iterate over lines from multiple input streamsstat— Interpretingstat()resultsfilecmp— File and Directory Comparisonstempfile— Generate temporary files and directoriesglob— Unix style pathname pattern expansionfnmatch— Unix filename pattern matchinglinecache— Random access to text linesshutil— High-level file operations
- Data Persistence
pickle— Python object serializationcopyreg— Registerpicklesupport functionsshelve— Python object persistencemarshal— Internal Python object serializationdbm— Interfaces to Unix “databases”sqlite3— DB-API 2.0 interface for SQLite databases- Tutorial
- Reference
- How-to guides
- How to use placeholders to bind values in SQL queries
- How to adapt custom Python types to SQLite values
- How to convert SQLite values to custom Python types
- Adapter and converter recipes
- How to use connection shortcut methods
- How to use the connection context manager
- How to work with SQLite URIs
- How to create and use row factories
- Explanation
- Data Compression and Archiving
- File Formats
- Cryptographic Services
- Generic Operating System Services
os— Miscellaneous operating system interfacesio— Core tools for working with streamstime— Time access and conversionsargparse— Parser for command-line options, arguments and sub-commandsgetopt— C-style parser for command line optionslogging— Logging facility for Pythonlogging.config— Logging configurationlogging.handlers— Logging handlersgetpass— Portable password inputcurses— Terminal handling for character-cell displayscurses.textpad— Text input widget for curses programscurses.ascii— Utilities for ASCII characterscurses.panel— A panel stack extension for cursesplatform— Access to underlying platform’s identifying dataerrno— Standard errno system symbolsctypes— A foreign function library for Python- ctypes tutorial
- Loading dynamic link libraries
- Accessing functions from loaded dlls
- Calling functions
- Fundamental data types
- Calling functions, continued
- Calling varadic functions
- Calling functions with your own custom data types
- Specifying the required argument types (function prototypes)
- Return types
- Passing pointers (or: passing parameters by reference)
- Structures and unions
- Structure/union alignment and byte order
- Bit fields in structures and unions
- Arrays
- Pointers
- Type conversions
- Incomplete Types
- Callback functions
- Accessing values exported from dlls
- Surprises
- Variable-sized data types
- ctypes reference
- ctypes tutorial
- Concurrent Execution
threading— Thread-based parallelismmultiprocessing— Process-based parallelismmultiprocessing.shared_memory— Shared memory for direct access across processes- The
concurrentpackage concurrent.futures— Launching parallel taskssubprocess— Subprocess managementsched— Event schedulerqueue— A synchronized queue classcontextvars— Context Variables_thread— Low-level threading API
- Networking and Interprocess Communication
asyncio— Asynchronous I/O- Runners
- Coroutines and Tasks
- Streams
- Synchronization Primitives
- Subprocesses
- Queues
- Exceptions
- Event Loop
- Event Loop Methods
- Running and stopping the loop
- Scheduling callbacks
- Scheduling delayed callbacks
- Creating Futures and Tasks
- Opening network connections
- Creating network servers
- Transferring files
- TLS Upgrade
- Watching file descriptors
- Working with socket objects directly
- DNS
- Working with pipes
- Unix signals
- Executing code in thread or process pools
- Error Handling API
- Enabling debug mode
- Running Subprocesses
- Callback Handles
- Server Objects
- Event Loop Implementations
- Examples
- Event Loop Methods
- Futures
- Transports and Protocols
- Policies
- Platform Support
- Extending
- High-level API Index
- Low-level API Index
- Developing with asyncio
socket— Low-level networking interfacessl— TLS/SSL wrapper for socket objectsselect— Waiting for I/O completionselectors— High-level I/O multiplexingsignal— Set handlers for asynchronous eventsmmap— Memory-mapped file support
- Internet Data Handling
email— An email and MIME handling packageemail.message: Representing an email messageemail.parser: Parsing email messagesemail.generator: Generating MIME documentsemail.policy: Policy Objectsemail.errors: Exception and Defect classesemail.headerregistry: Custom Header Objectsemail.contentmanager: Managing MIME Contentemail: Examplesemail.message.Message: Representing an email message using thecompat32APIemail.mime: Creating email and MIME objects from scratchemail.header: Internationalized headersemail.charset: Representing character setsemail.encoders: Encodersemail.utils: Miscellaneous utilitiesemail.iterators: Iterators
json— JSON encoder and decodermailbox— Manipulate mailboxes in various formatsmimetypes— Map filenames to MIME typesbase64— Base16, Base32, Base64, Base85 Data Encodingsbinascii— Convert between binary and ASCIIquopri— Encode and decode MIME quoted-printable data
- Structured Markup Processing Tools
html— HyperText Markup Language supporthtml.parser— Simple HTML and XHTML parserhtml.entities— Definitions of HTML general entities- XML Processing Modules
xml.etree.ElementTree— The ElementTree XML APIxml.dom— The Document Object Model APIxml.dom.minidom— Minimal DOM implementationxml.dom.pulldom— Support for building partial DOM treesxml.sax— Support for SAX2 parsersxml.sax.handler— Base classes for SAX handlersxml.sax.saxutils— SAX Utilitiesxml.sax.xmlreader— Interface for XML parsersxml.parsers.expat— Fast XML parsing using Expat
- Internet Protocols and Support
webbrowser— Convenient web-browser controllerwsgiref— WSGI Utilities and Reference Implementationurllib— URL handling modulesurllib.request— Extensible library for opening URLs- Request Objects
- OpenerDirector Objects
- BaseHandler Objects
- HTTPRedirectHandler Objects
- HTTPCookieProcessor Objects
- ProxyHandler Objects
- HTTPPasswordMgr Objects
- HTTPPasswordMgrWithPriorAuth Objects
- AbstractBasicAuthHandler Objects
- HTTPBasicAuthHandler Objects
- ProxyBasicAuthHandler Objects
- AbstractDigestAuthHandler Objects
- HTTPDigestAuthHandler Objects
- ProxyDigestAuthHandler Objects
- HTTPHandler Objects
- HTTPSHandler Objects
- FileHandler Objects
- DataHandler Objects
- FTPHandler Objects
- CacheFTPHandler Objects
- UnknownHandler Objects
- HTTPErrorProcessor Objects
- Examples
- Legacy interface
urllib.requestRestrictions
urllib.response— Response classes used by urlliburllib.parse— Parse URLs into componentsurllib.error— Exception classes raised by urllib.requesturllib.robotparser— Parser for robots.txthttp— HTTP moduleshttp.client— HTTP protocol clientftplib— FTP protocol clientpoplib— POP3 protocol clientimaplib— IMAP4 protocol clientsmtplib— SMTP protocol clientuuid— UUID objects according to RFC 4122socketserver— A framework for network servershttp.server— HTTP servershttp.cookies— HTTP state managementhttp.cookiejar— Cookie handling for HTTP clientsxmlrpc— XMLRPC server and client modulesxmlrpc.client— XML-RPC client accessxmlrpc.server— Basic XML-RPC serversipaddress— IPv4/IPv6 manipulation library
- Multimedia Services
- Internationalization
- Program Frameworks
turtle— Turtle graphicscmd— Support for line-oriented command interpretersshlex— Simple lexical analysis
- Graphical User Interfaces with Tk
tkinter— Python interface to Tcl/Tktkinter.colorchooser— Color choosing dialogtkinter.font— Tkinter font wrapper- Tkinter Dialogs
tkinter.messagebox— Tkinter message promptstkinter.scrolledtext— Scrolled Text Widgettkinter.dnd— Drag and drop supporttkinter.ttk— Tk themed widgetstkinter.tix— Extension widgets for Tk- IDLE
- Development Tools
typing— Support for type hints- Relevant PEPs
- Type aliases
- NewType
- Callable
- Generics
- User-defined generic types
- The
Anytype - Nominal vs structural subtyping
- Module contents
- Deprecation Timeline of Major Features
pydoc— Documentation generator and online help system- Python Development Mode
- Effects of the Python Development Mode
- ResourceWarning Example
- Bad file descriptor error example
doctest— Test interactive Python examplesunittest— Unit testing frameworkunittest.mock— mock object libraryunittest.mock— getting started- Using Mock
- Mock Patching Methods
- Mock for Method Calls on an Object
- Mocking Classes
- Naming your mocks
- Tracking all Calls
- Setting Return Values and Attributes
- Raising exceptions with mocks
- Side effect functions and iterables
- Mocking asynchronous iterators
- Mocking asynchronous context manager
- Creating a Mock from an Existing Object
- Patch Decorators
- Further Examples
- Mocking chained calls
- Partial mocking
- Mocking a Generator Method
- Applying the same patch to every test method
- Mocking Unbound Methods
- Checking multiple calls with mock
- Coping with mutable arguments
- Nesting Patches
- Mocking a dictionary with MagicMock
- Mock subclasses and their attributes
- Mocking imports with patch.dict
- Tracking order of calls and less verbose call assertions
- More complex argument matching
- Using Mock
- 2to3 — Automated Python 2 to 3 code translation
test— Regression tests package for Pythontest.support— Utilities for the Python test suitetest.support.socket_helper— Utilities for socket teststest.support.script_helper— Utilities for the Python execution teststest.support.bytecode_helper— Support tools for testing correct bytecode generationtest.support.threading_helper— Utilities for threading teststest.support.os_helper— Utilities for os teststest.support.import_helper— Utilities for import teststest.support.warnings_helper— Utilities for warnings tests
- Debugging and Profiling
- Software Packaging and Distribution
- Python Runtime Services
sys— System-specific parameters and functionssysconfig— Provide access to Python’s configuration informationbuiltins— Built-in objects__main__— Top-level code environmentwarnings— Warning controldataclasses— Data Classescontextlib— Utilities forwith-statement contextsabc— Abstract Base Classesatexit— Exit handlerstraceback— Print or retrieve a stack traceback__future__— Future statement definitionsgc— Garbage Collector interfaceinspect— Inspect live objectssite— Site-specific configuration hook
- Custom Python Interpreters
- Importing Modules
zipimport— Import modules from Zip archivespkgutil— Package extension utilitymodulefinder— Find modules used by a scriptrunpy— Locating and executing Python modulesimportlib— The implementation ofimportimportlib.resources– Resources- Deprecated functions
importlib.resources.abc– Abstract base classes for resources- Using
importlib.metadata - The initialization of the
sys.pathmodule search path
- Python Language Services
ast— Abstract Syntax Treessymtable— Access to the compiler’s symbol tablestoken— Constants used with Python parse treeskeyword— Testing for Python keywordstokenize— Tokenizer for Python sourcetabnanny— Detection of ambiguous indentationpyclbr— Python module browser supportpy_compile— Compile Python source filescompileall— Byte-compile Python librariesdis— Disassembler for Python bytecodepickletools— Tools for pickle developers
- MS Windows Specific Services
- Unix Specific Services
posix— The most common POSIX system callspwd— The password databasegrp— The group databasetermios— POSIX style tty controltty— Terminal control functionspty— Pseudo-terminal utilitiesfcntl— Thefcntlandioctlsystem callsresource— Resource usage informationsyslog— Unix syslog library routines
- Superseded Modules
aifc— Read and write AIFF and AIFC filesasynchat— Asynchronous socket command/response handlerasyncore— Asynchronous socket handleraudioop— Manipulate raw audio datacgi— Common Gateway Interface supportcgitb— Traceback manager for CGI scriptschunk— Read IFF chunked datacrypt— Function to check Unix passwordsimghdr— Determine the type of an imageimp— Access the import internalsmailcap— Mailcap file handlingmsilib— Read and write Microsoft Installer filesnis— Interface to Sun’s NIS (Yellow Pages)nntplib— NNTP protocol clientoptparse— Parser for command line options- Background
- Tutorial
- Reference Guide
- Option Callbacks
- Defining a callback option
- How callbacks are called
- Raising errors in a callback
- Callback example 1: trivial callback
- Callback example 2: check option order
- Callback example 3: check option order (generalized)
- Callback example 4: check arbitrary condition
- Callback example 5: fixed arguments
- Callback example 6: variable arguments
- Extending
optparse
ossaudiodev— Access to OSS-compatible audio devicespipes— Interface to shell pipelinessmtpd— SMTP Serversndhdr— Determine type of sound filespwd— The shadow password databasesunau— Read and write Sun AU filestelnetlib— Telnet clientuu— Encode and decode uuencode filesxdrlib— Encode and decode XDR data
- Security Considerations
- Extending and Embedding the Python Interpreter
- Recommended third party tools
- Creating extensions without third party tools
- 1. Extending Python with C or C++
- 1.1. A Simple Example
- 1.2. Intermezzo: Errors and Exceptions
- 1.3. Back to the Example
- 1.4. The Module’s Method Table and Initialization Function
- 1.5. Compilation and Linkage
- 1.6. Calling Python Functions from C
- 1.7. Extracting Parameters in Extension Functions
- 1.8. Keyword Parameters for Extension Functions
- 1.9. Building Arbitrary Values
- 1.10. Reference Counts
- 1.11. Writing Extensions in C++
- 1.12. Providing a C API for an Extension Module
- 2. Defining Extension Types: Tutorial
- 3. Defining Extension Types: Assorted Topics
- 4. Building C and C++ Extensions
- 5. Building C and C++ Extensions on Windows
- 1. Extending Python with C or C++
- Embedding the CPython runtime in a larger application
- Python/C API Reference Manual
- Introduction
- C API Stability
- The Very High Level Layer
- Reference Counting
- Exception Handling
- Utilities
- Abstract Objects Layer
- Concrete Objects Layer
- Fundamental Objects
- Numeric Objects
- Sequence Objects
- Container Objects
- Function Objects
- Other Objects
- Initialization, Finalization, and Threads
- Before Python Initialization
- Global configuration variables
- Initializing and finalizing the interpreter
- Process-wide parameters
- Thread State and the Global Interpreter Lock
- Sub-interpreter support
- Asynchronous Notifications
- Profiling and Tracing
- Advanced Debugger Support
- Thread Local Storage Support
- Python Initialization Configuration
- Memory Management
- Object Implementation Support
- API and ABI Versioning
- Distributing Python Modules
- Installing Python Modules
- Python HOWTOs
- Porting Python 2 Code to Python 3
- The Short Explanation
- Details
- Drop support for Python 2.6 and older
- Make sure you specify the proper version support in your
setup.pyfile - Have good test coverage
- Learn the differences between Python 2 & 3
- Update your code
- Prevent compatibility regressions
- Check which dependencies block your transition
- Update your
setup.pyfile to denote Python 3 compatibility - Use continuous integration to stay compatible
- Consider using optional static type checking
- Porting Extension Modules to Python 3
- Curses Programming with Python
- Descriptor HowTo Guide
- Enum HOWTO
- Programmatic access to enumeration members and their attributes
- Duplicating enum members and values
- Ensuring unique enumeration values
- Using automatic values
- Iteration
- Comparisons
- Allowed members and attributes of enumerations
- Restricted Enum subclassing
- Pickling
- Functional API
- Derived Enumerations
- When to use
__new__()vs.__init__() - How are Enums and Flags different?
- Enum Cookbook
- Subclassing EnumType
- Functional Programming HOWTO
- Logging HOWTO
- Logging Cookbook
- Using logging in multiple modules
- Logging from multiple threads
- Multiple handlers and formatters
- Logging to multiple destinations
- Custom handling of levels
- Configuration server example
- Dealing with handlers that block
- Sending and receiving logging events across a network
- Adding contextual information to your logging output
- Use of
contextvars - Imparting contextual information in handlers
- Logging to a single file from multiple processes
- Using file rotation
- Use of alternative formatting styles
- Customizing
LogRecord - Subclassing QueueHandler - a ZeroMQ example
- Subclassing QueueListener - a ZeroMQ example
- An example dictionary-based configuration
- Using a rotator and namer to customize log rotation processing
- A more elaborate multiprocessing example
- Inserting a BOM into messages sent to a SysLogHandler
- Implementing structured logging
- Customizing handlers with
dictConfig() - Using particular formatting styles throughout your application
- Configuring filters with
dictConfig() - Customized exception formatting
- Speaking logging messages
- Buffering logging messages and outputting them conditionally
- Sending logging messages to email, with buffering
- Formatting times using UTC (GMT) via configuration
- Using a context manager for selective logging
- A CLI application starter template
- A Qt GUI for logging
- Logging to syslog with RFC5424 support
- How to treat a logger like an output stream
- Patterns to avoid
- Other resources
- Regular Expression HOWTO
- Socket Programming HOWTO
- Sorting HOW TO
- Unicode HOWTO
- HOWTO Fetch Internet Resources Using The urllib Package
- Argparse Tutorial
- An introduction to the ipaddress module
- Argument Clinic How-To
- The Goals Of Argument Clinic
- Basic Concepts And Usage
- Converting Your First Function
- Advanced Topics
- Symbolic default values
- Renaming the C functions and variables generated by Argument Clinic
- Converting functions using PyArg_UnpackTuple
- Optional Groups
- Using real Argument Clinic converters, instead of “legacy converters”
- Py_buffer
- Advanced converters
- Parameter default values
- The
NULLdefault value - Expressions specified as default values
- Using a return converter
- Cloning existing functions
- Calling Python code
- Using a “self converter”
- Using a “defining class” converter
- Writing a custom converter
- Writing a custom return converter
- METH_O and METH_NOARGS
- tp_new and tp_init functions
- Changing and redirecting Clinic’s output
- The #ifdef trick
- Using Argument Clinic in Python files
- Instrumenting CPython with DTrace and SystemTap
- Annotations Best Practices
- Isolating Extension Modules
- Porting Python 2 Code to Python 3
- Python Frequently Asked Questions
- General Python FAQ
- Programming FAQ
- Design and History FAQ
- Why does Python use indentation for grouping of statements?
- Why am I getting strange results with simple arithmetic operations?
- Why are floating-point calculations so inaccurate?
- Why are Python strings immutable?
- Why must ‘self’ be used explicitly in method definitions and calls?
- Why can’t I use an assignment in an expression?
- Why does Python use methods for some functionality (e.g. list.index()) but functions for other (e.g. len(list))?
- Why is join() a string method instead of a list or tuple method?
- How fast are exceptions?
- Why isn’t there a switch or case statement in Python?
- Can’t you emulate threads in the interpreter instead of relying on an OS-specific thread implementation?
- Why can’t lambda expressions contain statements?
- Can Python be compiled to machine code, C or some other language?
- How does Python manage memory?
- Why doesn’t CPython use a more traditional garbage collection scheme?
- Why isn’t all memory freed when CPython exits?
- Why are there separate tuple and list data types?
- How are lists implemented in CPython?
- How are dictionaries implemented in CPython?
- Why must dictionary keys be immutable?
- Why doesn’t list.sort() return the sorted list?
- How do you specify and enforce an interface spec in Python?
- Why is there no goto?
- Why can’t raw strings (r-strings) end with a backslash?
- Why doesn’t Python have a “with” statement for attribute assignments?
- Why don’t generators support the with statement?
- Why are colons required for the if/while/def/class statements?
- Why does Python allow commas at the end of lists and tuples?
- Library and Extension FAQ
- Extending/Embedding FAQ
- Can I create my own functions in C?
- Can I create my own functions in C++?
- Writing C is hard; are there any alternatives?
- How can I execute arbitrary Python statements from C?
- How can I evaluate an arbitrary Python expression from C?
- How do I extract C values from a Python object?
- How do I use Py_BuildValue() to create a tuple of arbitrary length?
- How do I call an object’s method from C?
- How do I catch the output from PyErr_Print() (or anything that prints to stdout/stderr)?
- How do I access a module written in Python from C?
- How do I interface to C++ objects from Python?
- I added a module using the Setup file and the make fails; why?
- How do I debug an extension?
- I want to compile a Python module on my Linux system, but some files are missing. Why?
- How do I tell “incomplete input” from “invalid input”?
- How do I find undefined g++ symbols __builtin_new or __pure_virtual?
- Can I create an object class with some methods implemented in C and others in Python (e.g. through inheritance)?
- Python on Windows FAQ
- How do I run a Python program under Windows?
- How do I make Python scripts executable?
- Why does Python sometimes take so long to start?
- How do I make an executable from a Python script?
- Is a
*.pydfile the same as a DLL? - How can I embed Python into a Windows application?
- How do I keep editors from inserting tabs into my Python source?
- How do I check for a keypress without blocking?
- How do I solve the missing api-ms-win-crt-runtime-l1-1-0.dll error?
- Graphic User Interface FAQ
- “Why is Python Installed on my Computer?” FAQ
- Glossary
- About these documents
- Dealing with Bugs
- Copyright
- History and License