diff options
| -rw-r--r-- | Misc/NEWS | 102 |
1 files changed, 63 insertions, 39 deletions
@@ -1,7 +1,19 @@ What's New in Python 2.2a4? =========================== -Core +Type/class unification and new-style classes + +- pydoc and inspect are now aware of new-style classes; + e.g. help(list) at the interactive prompt now shows proper + documentation for all operations on list objects. + +- Applications using Jim Fulton's ExtensionClass module can now safely + be used with Python 2.2. In particular, Zope 2.4.1 now works with + Python 2.2 (as well as with Python 2.1.1). The Demo/metaclass + examples also work again. It is hoped that Gtk and Boost also work + with 2.2a4 and beyond. (If you can confirm this, please write + webmaster@python.org; if there are still problems, please open a bug + report on SourceForge.) - property() now takes 4 keyword arguments: fget, fset, fdel and doc. These map to readonly attributes 'fget', 'fset', 'fdel', and '__doc__' @@ -9,6 +21,56 @@ Core discoverable from Python in 2.2a3. __doc__ is new, and allows to associate a docstring with a property. +- Comparison overloading is now more completely implemented. For + example, a str subclass instance can properly be compared to a str + instance, and it can properly overload comparison. Ditto for most + other built-in object types. + +- The repr() of new-style classes has changed; instead of <type + 'M.Foo'> a new-style class is now rendered as <class 'M.Foo'>, + *except* for built-in types, which are still rendered as <type + 'Foo'> (to avoid upsetting existing code that might parse or + otherwise rely on repr() of certain type objects). + +- The repr() of new-style objects is now always <Foo object at XXX>; + previously, it was sometimes <Foo instance at XXX>. + +- For new-style classes, what was previously called __getattr__ is now + called __getattribute__. This method, if defined, is called for + *every* attribute access. A new __getattr__ hook mor similar to the + one in classic classes is defined which is called only if regular + attribute access raises AttributeError; to catch *all* attribute + access, you can use __getattribute__ (for new-style classes). If + both are defined, __getattribute__ is called first, and if it raises + AttributeError, __getattr__ is called. + +- The __class__ attribute of new-style objects can be assigned to. + The new class must have the same C-level object layout as the old + class. + +- The builtin file type can be subclassed now. In the usual pattern, + "file" is the name of the builtin type, and file() is a new builtin + constructor, with the same signature as the builtin open() function. + file() is now the preferred way to open a file. + +- Previously, __new__ would only see sequential arguments passed to + the type in a constructor call; __init__ would see both sequential + and keyword arguments. This made no sense whatsoever any more, so + now both __new__ and __init__ see all arguments. + +- Previously, hash() applied to an instance of a subclass of str or + unicode always returned 0. This has been repaired. + +- Previously, an operation on an instance of a subclass of an + immutable type (int, long, float, complex, tuple, str, unicode), + where the subtype didn't override the operation (and so the + operation was handled by the builtin type), could return that + instance instead a value of the base type. For example, if s was of + a str sublass type, s[:] returned s as-is. Now it returns a str + with the same value as s. + +Core + - file.writelines() now accepts any iterable object producing strings. - PyUnicode_FromEncodedObject() now works very much like @@ -22,40 +84,6 @@ Core of a print statement must support Unicode objects, i.e. they must at least convert them into ASCII strings. -- The builtin file type can be subclassed now. In the usual pattern, - "file" is the name of the builtin type, and file() is a new builtin - constructor, with the same signature as the builtin open() function. - file() is now the preferred way to open a file. - -- In 2.2a3, *for new-style classes only*, __getattr__ was called for - every attribute access. This was confusing because it differed - significantly from the behavior of classic classes, where it was - only called for missing attributes. Now, __getattr__ is called only - if regular attribute access raises AttributeError; to catch *all* - attribute access, *for new-style classes only*, you can use - __getattribute__. If both are defined, __getattribute__ is called - first, and if it raises AttributeError, __getattr__ is called. - -- In 2.2a3, __new__ would only see sequential arguments passed to the - type in a constructor call; __init__ would see both sequential and - keyword arguments. This made no sense whatsoever any more, so - now both __new__ and __init__ see all arguments. - -- In 2.2a3, hash() applied to an instance of a subclass of str or unicode - always returned 0. This has been repaired. - -- In 2.2a3, an operation on an instance of a subclass of an immutable type - (int, long, float, complex, tuple, str, unicode), where the subtype - didn't override the operation (and so the operation was handled by the - builtin type), could return that instance instead a value of the base - type. For example, if s was of a str sublass type, s[:] returned s - as-is. Now it returns a str with the same value as s. - -- Applications using Jim Fulton's ExtensionClass module can now safely - be used with Python 2.2. In particular, Zope 2.4.1 now works with - Python 2.2 (as well as with Python 2.1.1). The Demo/metaclass - examples also work again. - - Thread scheduling on Solaris should be improved; it is no longer necessary to insert a small sleep at the start of a thread in order to let other runnable threads be scheduled. @@ -102,10 +130,6 @@ Library Tool to a standard library package. (Tools/compiler still exists as a sample driver.) -- pydoc and inspect are now aware of new-style classes; - e.g. help(list) at the interactive prompt now shows proper - documentation for all operations on list objects. - Tools Build |