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| * Reduce feature duplication: * string module vs. string methods * xrange() vs range() * int vs. long * 8 bit vs. Unicode strings * map/filter/reduce vs. list comprehensions * lambda vs. def * Library reorganization * Return iterators instead of lists * d.keys(), .values(), .items() * range(), zip(), map(), filter() * Consume iterators * min(), max() * Optional static typing? * Support only new-style classes; classic classes will be gone. * Remove string exceptions, `x` for repr(x), sys.exc_type, coerce(), other deprecated stuff * print as a function -- write(x,y,z), writeln(x,y,z) |
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| == Rearrangements == | == Core Language Changes == |
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| intern(), id(): put in sys | * Remove distinction between `int` and `long` types. * Make all strings unicode, and have a separate bytes type. * 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]] * Remove support for old-style classes--all classes will be new-style. * Remove {{{`x`}}} in favor of `repr(x)`. [[#a 1]] * Remove the `lambda` statement. [[#a 1]] * Remove support for string exceptions. * Perhaps have optional declarations for static typing. * Do something so you can catch multiple exceptions using 'except E1, E2, E3:'. Maybe 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) }}} |
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| xrange(): make range() return an iterator | == Built-In Changes == |
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| buffer(): must die (use bytes, PEP 296) | * Have `range()`, `zip()`, `dict.keys()`, `dict.items()`, and `dict.values()` return iterators. * Remove `dict.iteritems()`, `dict.iterkeys()`, `dict.itervalues()`. * Change `max()` and `min()` to consume iterators. * Remove `apply()`. Use `f(*args, **kw)` instead. [[#a 1]] * Remove `xrange()`. Use `range()` instead. [[#a 1]] * Remove `map()` and `filter()`. Use list comprehensions instead. [[#a 1]] * Remove `coerce()` as it is obsolete. [[#a 1]] * Remove `reduce()`. Use a loop instead. [[#a 1]] * Remove `callable()`. Catch the exception instead. [[#a 1]] * Remove `buffer()` in favor of a new `bytes` type. [[#a 1]] * Remove `raw_input()`. Use `sys.stdin.readline()` instead. [[#a 1]] * Remove `input()`. Use 'eval(sys.stdin.readline())` instead. [[#a 1]] * Remove `execfile()` and `reload()`. Use `exec()` instead. [[#a 1]] * Move `compile()`, `intern()` and `id()` to the `sys` module. [[#a 1]] |
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| raw_input(): use sys.stdin.readline() | == Standard Library Changes == |
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| input(): use eval(sys.stdin.readline()) | * Remove `string` and other deprecated modules. * Remove `sys.exc_type` as it is not type safe. Use `sys.exc_info` instead. [[#a 1]] |
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| callable(): just call it, already | == Unresolved Issues == |
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| execfile(), reload(): use exec() | * `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? |
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| compile(): put in sys | == References == |
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| exec as a statement is not worth it -- make it a function |
* [[Anchor(a)]] [1] Python Regrets: http://www.python.org/doc/essays/ppt/regrets/PythonRegrets.pdf |
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.)
See the "Python Regrets" talk and other recent presentations by Guido.
Core Language Changes
Remove distinction between int and long types.
- Make all strings unicode, and have a separate bytes type.
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
- Remove support for old-style classes--all classes will be new-style.
Remove `x` in favor of repr(x). #a 1
Remove the lambda statement. #a 1
- Remove support for string exceptions.
- Perhaps have optional declarations for static typing.
- Do something so you can catch multiple exceptions using 'except E1, E2, E3:'. Maybe 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)
Built-In Changes
Have range(), zip(), dict.keys(), dict.items(), and dict.values() return iterators.
Remove dict.iteritems(), dict.iterkeys(), dict.itervalues().
Change max() and min() to consume iterators.
Remove apply(). Use f(*args, **kw) instead. #a 1
Remove xrange(). Use range() instead. #a 1
Remove map() and filter(). Use list comprehensions instead. #a 1
Remove coerce() as it is obsolete. #a 1
Remove reduce(). Use a loop instead. #a 1
Remove callable(). Catch the exception instead. #a 1
Remove buffer() in favor of a new bytes type. #a 1
Remove raw_input(). Use sys.stdin.readline() instead. #a 1
Remove input(). Use 'eval(sys.stdin.readline())` instead. #a 1
Remove execfile() and reload(). Use exec() instead. #a 1
Move compile(), intern() and id() to the sys module. #a 1
Standard Library Changes
Remove string and other deprecated modules.
Remove sys.exc_type as it is not type safe. Use sys.exc_info instead. #a 1
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?
References
Anchor(a) [1] Python Regrets: http://www.python.org/doc/essays/ppt/regrets/PythonRegrets.pdf