Title:Python 3.0 Plans
Last-Modified:2006-01-03 00:22:57 -0800 (Tue, 03 Jan 2006)
Author:A.M. Kuchling <amk at>, Brett Cannon <drifty at>



This PEP describes the changes currently envisioned in Python 3.0 (also called Python 3000), a hypothetical future release of Python that can break backwards compatibility with the existing body of Python code.

The list of features included in this document is subject to change and isn't binding on the Python development community; features may be added, removed, and modified at any time. The purpose of this list is to focus our language development effort on changes that are steps to 3.0, and to encourage people to invent ways to smooth the transition.

This document is not a wish-list that anyone can extend. While there are two authors of this PEP, we're just supplying the text; the decisions for which changes are listed in this document are made by Guido van Rossum, who has chosen them as goals for Python 3.0.

General goals

A general goal is to reduce feature duplication by removing old ways of doing things. A general principle of the design will be that one obvious way of doing something is enough. [1]

Core language

To be removed:

Built-in Namespace

To be removed:

Atomic Types

To be removed:

Standard library

To be removed:


[1](1, 2, 3, 4, 5, 6, 7, 8) PyCon 2003 State of the Union:
[2](1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13) Python Regrets:
[3](1, 2) Python Wiki:
[4]python-dev email ("Constancy of None")
[5]python-dev email (' "as" to be a keyword?')
[6]python-dev email ("Comparing heterogeneous types")
[7]python-dev email ("Let's get rid of unbound methods")
[8]python-dev email ("Fixing _PyEval_SliceIndex so that integer-like objects can be used")
[9](1, 2, 3) Guido's blog ("The fate of reduce() in Python 3000")
[10]PEP 238 ("Changing the Division Operator")
[11]Guido's blog ("Python Optional Typechecking Redux")
[12]PEP 289 ("Generator Expressions")
[13](1, 2) python-dev email ("anonymous blocks")
[14]python-dev email ("PEP 8: exception style")
[15]python-dev email (Remove str.find in 3.0?)
[16]python-dev email (Replacement for print in Python 3.0)
[17](1, 2, 3, 4, 5, 6, 7) Python docs
[18](1, 2, 3) PEP 4 ("Deprecation of Standard Modules")
[19]PEP 328 ("Imports: Multi-Line and Absolute/Relative")
[20]PEP 352 ("Required Superclass for Exceptions")