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Diffstat (limited to 'Doc')
-rw-r--r-- | Doc/whatsnew/whatsnew22.tex | 87 |
1 files changed, 69 insertions, 18 deletions
diff --git a/Doc/whatsnew/whatsnew22.tex b/Doc/whatsnew/whatsnew22.tex index 6645fbe..51697a1 100644 --- a/Doc/whatsnew/whatsnew22.tex +++ b/Doc/whatsnew/whatsnew22.tex @@ -17,39 +17,45 @@ for Python 2.2 alpha 1. Please send any comments, bug reports, or questions, no matter how minor, to \email{akuchlin@mems-exchange.org}. } -This article explains the new features in Python 2.2. Python 2.2 -includes some significant changes that go far toward cleaning up the -language's darkest corners, and some exciting new features. +This article explains the new features in Python 2.2. + +Python 2.2 can be thought of as the "cleanup release". There are some +features such as generators and iterators that are completely new, but +most of the changes, significant and far-reaching though they may be, +are aimed at cleaning up irregularities and dark corners of the +language design. This article doesn't attempt to provide a complete specification for -the new features, but instead provides a convenient overview of the -new features. For full details, you should refer to 2.2 documentation +the new features, but instead provides a convenient overview. For +full details, you should refer to the documentation for Python 2.2, such as the \citetitle[http://python.sourceforge.net/devel-docs/lib/lib.html]{Python Library Reference} and the \citetitle[http://python.sourceforge.net/devel-docs/ref/ref.html]{Python -Reference Manual}, or to the PEP for a particular new feature. -% These \citetitle marks should get the python.org URLs for the final +Reference Manual}. +% XXX These \citetitle marks should get the python.org URLs for the final % release, just as soon as the docs are published there. +If you want to understand the complete implementation and design +rationale for a change, refer to the PEP for a particular new feature. The final release of Python 2.2 is planned for October 2001. %====================================================================== -% It looks like this set of changes will likely get into 2.2, -% so I need to read and digest the relevant PEPs. -%\section{PEP 252: Type and Class Changes} +\section{PEP 252: Type and Class Changes} + +XXX -%XXX +I need to read and digest the relevant PEPs. -% GvR's description at http://www.python.org/2.2/descrintro.html +GvR's description at http://www.python.org/2.2/descrintro.html -%\begin{seealso} +\begin{seealso} -%\seepep{252}{Making Types Look More Like Classes}{Written and implemented -%by GvR.} +\seepep{252}{Making Types Look More Like Classes}{Written and implemented +by Guido van Rossum.} -%\end{seealso} +\end{seealso} %====================================================================== @@ -341,8 +347,47 @@ and Tim Peters, with other fixes from the Python Labs crew.} %====================================================================== \section{PEP 237: Unifying Long Integers and Integers} -XXX write this section +In recent versions, the distinction between regular integers, which +are 32-bit values on most machines, and long integers, which can be of +arbitrary size, was becoming an annoyance. For example, on platforms +that support large files (files larger than \code{2**32} bytes), the +\method{tell()} method of file objects has to return a long integer. +However, there were various bits of Python that expected plain +integers and would raise an error if a long integer was provided +instead. For example, in version XXX of Python, only regular integers +could be used as a slice index, and \code{'abc'[1L:]} would raise a +\exception{TypeError} exception with the message 'slice index must be +int'. + +Python 2.2 will shift values from short to long integers as required. +The 'L' suffix is no longer needed to indicate a long integer literal, +as now the compiler will choose the appropriate type. (Using the 'L' +suffix will be discouraged in future 2.x versions of Python, +triggering a warning in Python 2.4, and probably dropped in Python +3.0.) Many operations that used to raise an \exception{OverflowError} +will now return a long integer as their result. For example: + +\begin{verbatim} +>>> 1234567890123 +XXX +>>> 2 ** 32 +XXX put output here +\end{verbatim} +In most cases, integers and long integers will now be treated +identically. You can still distinguish them with the +\function{type()} built-in function, but that's rarely needed. The +\function{int()} function will now return a long integer if the value +is large enough. + +% XXX is there a warning-enabling command-line option for this? + +\begin{seealso} + +\seepep{237}{Unifying Long Integers and Integers}{Written by +Moshe Zadka and Guido van Rossum. Implemented mostly by Guido van Rossum.} + +\end{seealso} %====================================================================== \section{PEP 238: Changing the Division Operator} @@ -858,7 +903,13 @@ to experiment with these modules can uncomment them manually. by \cfunction{dlopen()} using the \function{sys.getdlopenflags()} and \function{sys.setdlopenflags()} functions. (Contributed by Bram Stolk.) - \item XXX 3-argument float pow() is gone + \item The \function{pow()} built-in function no longer supports 3 + arguments when floating-point numbers are supplied. + \code{pow(\var{x}, \var{y}, \var{z})} returns \code{(x**y) % z}, but + this is never useful for floating point numbers, and the final + result varies unpredictably depending on the platform. A call such + as \code{pow(2.0, 8.0, 7.0)} will now raise a \exception{XXX} + exception. \end{itemize} |