This page lists features that GvR has mentioned as goals for Python 3.0. This page has been consolidated into PEP 3000; the PEP is more up-to-date and is actively maintained. #e 5

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

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• Remove coerce() as it is obsolete.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