Author: andrew.kuchling Date: Wed Aug 16 15:22:20 2006 New Revision: 51313 Modified: python/trunk/Doc/whatsnew/whatsnew25.tex Log: Add UnicodeWarning Modified: python/trunk/Doc/whatsnew/whatsnew25.tex ============================================================================== --- python/trunk/Doc/whatsnew/whatsnew25.tex (original) +++ python/trunk/Doc/whatsnew/whatsnew25.tex Wed Aug 16 15:22:20 2006 @@ -1184,6 +1184,35 @@ # -*- coding: latin1 -*- \end{verbatim} +\item A new warning, \class{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. +The result of the comparison is false: + +\begin{verbatim} +>>> chr(128) == unichr(128) # Can't convert chr(128) to Unicode +__main__:1: UnicodeWarning: Unicode equal comparison failed + to convert both arguments to Unicode - interpreting them + as being unequal +False +>>> chr(127) == unichr(127) # chr(127) can be converted +True +\end{verbatim} + +Previously this would raise a \class{UnicodeDecodeError} exception, +but in 2.5 this could result in puzzling problems when accessing a +dictionary. If you looked up \code{unichr(128)} and \code{chr(128)} +was being used as a key, you'd get a \class{UnicodeDecodeError} +exception. Other changes in 2.5 resulted in this exception being +raised instead of suppressed by the code in \file{dictobject.c} that +implements dictionaries. + +Raising an exception for such a comparison is strictly correct, but +the change might have broken code, so instead +\class{UnicodeWarning} was introduced. + +(Implemented by Marc-Andr\'e Lemburg.) + \item One error that Python programmers sometimes make is forgetting to include an \file{__init__.py} module in a package directory. Debugging this mistake can be confusing, and usually requires running @@ -2423,6 +2452,11 @@ described in section~\ref{pep-342}, it's now possible for \member{gi_frame} to be \code{None}. +\item A new warning, \class{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 \class{UnicodeDecodeError} exception. + \item Library: the \module{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