21 Porting to Python 2.3

This section lists previously described changes that may require changes to your code:

yield is now always a keyword; if it's used as a variable name in your code, a different name must be chosen.

For strings X and Y, X in Y now works if X is more than one character long.

The int() type constructor will now return a long integer instead of raising an OverflowError when a string or floating-point number is too large to fit into an integer.

If you have Unicode strings that contain 8-bit characters, you must declare the file's encoding (UTF-8, Latin-1, or whatever) by adding a comment to the top of the file. See section 3 for more information.

Calling Tcl methods through _tkinter no longer returns only strings. Instead, if Tcl returns other objects those objects are converted to their Python equivalent, if one exists, or wrapped with a _tkinter.Tcl_Obj object if no Python equivalent exists.

Large octal and hex literals such as 0xffffffff now trigger a FutureWarning. Currently they're stored as 32-bit numbers and result in a negative value, but in Python 2.4 they'll become positive long integers.

There are a few ways to fix this warning. If you really need a positive number, just add an "L" to the end of the literal. If you're trying to get a 32-bit integer with low bits set and have previously used an expression such as ~(1 << 31), it's probably clearest to start with all bits set and clear the desired upper bits. For example, to clear just the top bit (bit 31), you could write 0xffffffffL &~(1L<<31).

You can no longer disable assertions by assigning to __debug__.

The Distutils setup() function has gained various new keyword arguments such as depends. Old versions of the Distutils will abort if passed unknown keywords. A solution is to check for the presence of the new get_distutil_options() function in your setup.py and only uses the new keywords with a version of the Distutils that supports them:

from distutils import core

kw = {'sources': 'foo.c', ...}
if hasattr(core, 'get_distutil_options'):
    kw['depends'] = ['foo.h']
ext = Extension(**kw)

Using None as a variable name will now result in a SyntaxWarning warning.

Names of extension types defined by the modules included with Python now contain the module and a "." in front of the type name.

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