What’s New In Python 3.11

Release 3.11.2
Date February 28, 2023
Editor Pablo Galindo Salgado

This article explains the new features in Python 3.11, compared to 3.10.

Summary – Release highlights

• Python 3.11 is between 10-60% faster than Python 3.10. On average, we measured a 1.25x speedup on the standard benchmark suite.
  

New syntax features:

• PEP 654: Exception Groups and except*
  

New built-in features:

• PEP 678: Exceptions can be enriched with notes
  

New standard library modules:

• PEP 680: tomllib— Support for parsing TOML in the Standard Library
  

Interpreter improvements:

• PEP 657: Fine-grained error locations in tracebacks
  
• New -Pcommand line option and \PYTHONSAFEPATHenvironment variable to disable automatically
  
• prepending potentially unsafe paths to sys.path
  
  

New typing features:

• PEP 646: Variadic generics
  
• PEP 655: Marking individual TypedDict items as required or not-required
  
• PEP 673: Self type
  
• PEP 675: Arbitrary literal string type
  
• PEP 681: Data class transforms
  

Important deprecations, removals and restrictions:

• PEP 594: Many legacy standard library modules have been deprecated and will be removed in Python 3.13
  
• PEP 624: Py_UNICODE encoder APIs have been removed
  
• PEP 670: Macros converted to static inline functions
  

New Features

PEP 657: Fine-grained error locations in tracebacks

When printing tracebacks, the interpreter will now point to the exact expression that caused the error, instead of just the line. For example:

Traceback (most recent call last):
  File "distance.py", line 11, in <module>
    print(manhattan_distance(p1, p2))
          ^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "distance.py", line 6, in manhattan_distance
    return abs(point_1.x - point_2.x) + abs(point_1.y - point_2.y)
                         
AttributeError: 'NoneType' object has no attribute 'x'


Previous versions of the interpreter would point to just the line, making it ambiguous which object was None
. These enhanced errors can also be helpful when dealing with deeply nested dict
objects and multiple function calls:

Traceback (most recent call last):
  File "query.py", line 37, in <module>
    magic_arithmetic('foo')
  File "query.py", line 18, in magic_arithmetic
    return add_counts(x) / 25
          ^^^^^^^^^^^^^
  File "query.py", line 24, in add_counts
    return 25 + query_user(user1) + query_user(user2)
                ^^^^^^^^^^^^^^^^^
  File "query.py", line 32, in query_user
    return 1 + query_count(db, response['a']['b']['c']['user'], retry=True)
                              ~~~~~~~~~~~~~~~~~~^^^^^
TypeError: 'NoneType' object is not subscriptable


As well as complex arithmetic expressions:

Traceback (most recent call last):
  File "calculation.py", line 54, in <module>
    result = (x / y / z) * (a / b / c)
              ~~~~~~^~~
ZeroDivisionError: division by zero


Additionally, the information used by the enhanced traceback feature is made available via a general API, that can be used to correlate bytecode instructions with source code location. This information can be retrieved using:

• The codeobject.co_positions() method in Python.
  
• The PyCode_Addr2Location()function in the C API.