[Py-howto-checkins] CVS: pyhowto python-22.tex,1.26,1.27

[A.M. K. <aku...@us...>]

Update of /cvsroot/py-howto/pyhowto
In directory usw-pr-cvs1:/tmp/cvs-serv9267

Modified Files:
	python-22.tex 
Log Message:
Add section on long integer changes
Add removal of 3-arg pow() for floats
Rewrite introduction a bit


Index: python-22.tex
===================================================================
RCS file: /cvsroot/py-howto/pyhowto/python-22.tex,v
retrieving revision 1.26
retrieving revision 1.27
diff -C2 -r1.26 -r1.27
*** python-22.tex	2001/09/05 14:53:31	1.26
--- python-22.tex	2001/09/10 03:20:53	1.27
***************
*** 18,35 ****
  }
  
! 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 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
  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
  % release, just as soon as the docs are published there.
  
  The final release of Python 2.2 is planned for October 2001.
--- 18,41 ----
  }
  
! 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.  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}.   
! % 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.
***************
*** 37,56 ****
  
  %======================================================================
! % 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}
  
! %XXX
  
! % GvR's description at http://www.python.org/2.2/descrintro.html
  
! %\begin{seealso}
  
! %\seepep{252}{Making Types Look More Like Classes}{Written and implemented 
! %by GvR.}
  
! %\end{seealso}
  
  
  %======================================================================
  \section{PEP 234: Iterators}
--- 43,62 ----
  
  %======================================================================
! \section{PEP 252: Type and Class Changes}
  
! XXX
  
! I need to read and digest the relevant PEPs.
  
! GvR's description at http://www.python.org/2.2/descrintro.html
  
! \begin{seealso}
  
! \seepep{252}{Making Types Look More Like Classes}{Written and implemented 
! by Guido van Rossum.}
  
+ \end{seealso}
  
+ 
  %======================================================================
  \section{PEP 234: Iterators}
***************
*** 341,347 ****
  %======================================================================
  \section{PEP 237: Unifying Long Integers and Integers}
  
! XXX write this section
  
  
  %======================================================================
--- 347,392 ----
  %======================================================================
  \section{PEP 237: Unifying Long Integers and Integers}
+ 
+ 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}
  
  %======================================================================
***************
*** 859,863 ****
    \function{sys.setdlopenflags()} functions.    (Contributed by Bram Stolk.)
  
!   \item XXX 3-argument float pow() is gone
    
  \end{itemize}
--- 904,914 ----
    \function{sys.setdlopenflags()} functions.    (Contributed by Bram Stolk.)
  
!   \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}