This page lists features that GvR has mentioned as goals for Python 3.0.

(Another list is at PythonThreeDotOh, but it incorporates items that GvR has never talked about.)

This will eventually be consolidated into PEP 3000. #e 5

Core Language Changes

• Remove distinction between int and long types. #a 4

• Make all strings unicode, and have a separate bytes type. #a 2 #a 4

• Replace all old-style classes. #a 4

• Make the exec statement a function (again.) #a 1

• Make the print statement a function. (write(x,y,z), writeln(x,y,z)) #a 1

• Do something so you can catch multiple exceptions using except E1, E2, E3:. Perhaps use except E1, E2, E3 as err: if you want the error variable. (Added by GvR, suggested by Bram Cohen.)

• Add a with statement:

  with self:
      .foo = [1, 2, 3]
      .bar(4, .foo)

• Remove `x`. #a 1

  • Alternatively: use repr(x). Reasoning: backticks are hard to read in many fonts and can be mangled by typesetting software.

• Remove the lambda statement. #a 1 #a 4

  • Alternatively: use a local function.

    Reasoning: lambda supports only one statement.

• Remove support for string exceptions. #a 1

  • Alternatively: use a class.
• Perhaps have optional declarations for static typing.

  • One suggestion is to [http://mail.python.org/pipermail/python-dev/2004-February/042795.html use an "as" keyword for this] and for adaptation ([http://www.python.org/peps/pep-0246.html PEP 246]):

    "x as y" means: adapt x to the y protocol
    
    def foo (a as int, b as float) as float:
        a2 = a as float # same as: adapt(a,float)
        ...

Built-In Changes

• Have range(), zip(), dict.keys(), dict.items(), and dict.values() return iterators.

• Move compile(), intern() and id() to the sys module. #a 1

• Change max() and min() to consume iterators.

• Remove dict.iteritems(), dict.iterkeys(), and dict.itervalues().

  • Alternatively: use dict.items(), dict.keys(), and dict.values() respectively.

• Remove apply(). #a 1

  • Alternatively: use f(*args, **kw).

• Remove xrange(). #a 1 #a 4

  • Alternatively: use range().

• Remove map() and filter(). #a 1 #a 4

  • Alternatively: use list comprehensions.

• Remove coerce() as it is obsolete. #a 1

• Remove reduce(). #a 1

  • Alternatively: use a loop.

• Remove callable(). #a 1

  • Alternatively: catch the exception.

• Remove buffer(). #a 1 #a 2

  • Alternatively: use new bytes type.

• Remove raw_input(). #a 1

  • Alternatively: use sys.stdin.readline().

• Remove input(). #a 1

  • Alternatively: use eval(sys.stdin.readline()).

• Remove execfile() and reload(). #a 1

  • Alternatively: use exec().

Standard Library Changes

• Remove string module. #c 4

  • Alternatively: use string methods.

• Remove other deprecated modules. #c 3

• Remove sys.exc_type. #a 1

  • Alternatively: use sys.exc_info. Reasoning: it is not thread safe.

Unresolved Issues

• L += x and L.extend(x) are equivalent.

• Can the order of parameter of the insert method be changed so the the index parameter is optional and list.append can be removed?

• What is the status of the <> operator? Answer: it's dead. (GvR)

References

• Anchor(a) [1] Python Regrets: http://www.python.org/doc/essays/ppt/regrets/PythonRegrets.pdf

• Anchor(b) [2] PEP 296 -- Adding a bytes Object Type: http://python.org/peps/pep-0296.html

• Anchor(c) [3] PEP 4 -- Deprecation of Standard Modules: http://python.org/peps/pep-0004.html

• Anchor(d) [4] PyCon 2003 State of the Union Address: http://www.python.org/doc/essays/ppt/pycon2003/pycon2003.ppt

• Anchor(e) [5] PEP 3000 -- Python 3.0 Plans: http://python.org/peps/pep-3000.html