This section lists previously described changes that may require
changes to your code:
ASCII is now the default encoding for modules. It's now
a syntax error if a module contains string literals with 8-bit
characters but doesn't have an encoding declaration. In Python 2.4
this triggered a warning, not a syntax error.
Previously, the gi_frame attribute of a generator
was always a frame object. Because of the PEP 342 changes
described in section 7, it's now possible
for gi_frame to be None.
A new warning, UnicodeWarning, is triggered when
you attempt to compare a Unicode string and an 8-bit string that can't
be converted to Unicode using the default ASCII encoding. Previously
such comparisons would raise a UnicodeDecodeError exception.
Library: the csv module is now stricter about multi-line quoted
fields. If your files contain newlines embedded within fields, the
input should be split into lines in a manner which preserves the
Library: the locale module's
format() function's would previously
accept any string as long as no more than one %char specifier
appeared. In Python 2.5, the argument must be exactly one %char
specifier with no surrounding text.
Library: The pickle and cPickle modules no
longer accept a return value of None from the
__reduce__() method; the method must return a tuple of
arguments instead. The modules also no longer accept the deprecated
bin keyword parameter.
Library: The SimpleXMLRPCServer and DocXMLRPCServer
classes now have a rpc_paths attribute that constrains
XML-RPC operations to a limited set of URL paths; the default is
to allow only '/' and '/RPC2'. Setting
rpc_paths to None or an empty tuple disables
this path checking.
C API: Many functions now use Py_ssize_t
instead of int to allow processing more data on 64-bit
machines. Extension code may need to make the same change to avoid
warnings and to support 64-bit machines. See the earlier
section 10 for a discussion of this change.
The obmalloc changes mean that
you must be careful to not mix usage
of the PyMem_*() and PyObject_*()
families of functions. Memory allocated with
one family's *_Malloc() must be
freed with the corresponding family's *_Free() function.