source: trunk/essentials/dev-lang/python/README@ 3368

This is Python version 2.5
==========================

Copyright (c) 2001, 2002, 2003, 2004, 2005, 2006 Python Software Foundation.
All rights reserved.

Copyright (c) 2000 BeOpen.com.
All rights reserved.

Copyright (c) 1995-2001 Corporation for National Research Initiatives.
All rights reserved.

Copyright (c) 1991-1995 Stichting Mathematisch Centrum.
All rights reserved.


License information
-------------------

See the file "LICENSE" for information on the history of this
software, terms & conditions for usage, and a DISCLAIMER OF ALL
WARRANTIES.

This Python distribution contains no GNU General Public Licensed
(GPLed) code so it may be used in proprietary projects just like prior
Python distributions.  There are interfaces to some GNU code but these
are entirely optional.

All trademarks referenced herein are property of their respective
holders.


What's new in this release?
---------------------------

See the file "Misc/NEWS".


If you don't read instructions
------------------------------

Congratulations on getting this far. :-)

To start building right away (on UNIX): type "./configure" in the
current directory and when it finishes, type "make".  This creates an
executable "./python"; to install in /usr/local, first do "su root"
and then "make install".

The section `Build instructions' below is still recommended reading.


What is Python anyway?
----------------------

Python is an interpreted, interactive object-oriented programming
language suitable (amongst other uses) for distributed application
development, scripting, numeric computing and system testing.  Python
is often compared to Tcl, Perl, Java, JavaScript, Visual Basic or
Scheme.  To find out more about what Python can do for you, point your
browser to http://www.python.org/.


How do I learn Python?
----------------------

The official tutorial is still a good place to start; see
http://docs.python.org/ for online and downloadable versions, as well
as a list of other introductions, and reference documentation.

There's a quickly growing set of books on Python.  See
http://wiki.python.org/moin/PythonBooks for a list.


Documentation
-------------

All documentation is provided online in a variety of formats.  In
order of importance for new users: Tutorial, Library Reference,
Language Reference, Extending & Embedding, and the Python/C API.  The
Library Reference is especially of immense value since much of
Python's power is described there, including the built-in data types
and functions!

All documentation is also available online at the Python web site
(http://docs.python.org/, see below).  It is available online for
occasional reference, or can be downloaded in many formats for faster
access.  The documentation is available in HTML, PostScript, PDF, and
LaTeX formats; the LaTeX version is primarily for documentation
authors, translators, and people with special formatting requirements.

Unfortunately, new-style classes (new in Python 2.2) have not yet been
integrated into Python's standard documentation.  A collection of
pointers to what has been written is at:

    http://www.python.org/doc/newstyle.html


Web sites
---------

New Python releases and related technologies are published at
http://www.python.org/.  Come visit us!

There's also a Python community web site at
http://starship.python.net/.


Newsgroups and Mailing Lists
----------------------------

Read comp.lang.python, a high-volume discussion newsgroup about
Python, or comp.lang.python.announce, a low-volume moderated newsgroup
for Python-related announcements.  These are also accessible as
mailing lists: see http://www.python.org/community/lists.html for an
overview of these and many other Python-related mailing lists.

Archives are accessible via the Google Groups Usenet archive; see
http://groups.google.com/.  The mailing lists are also archived, see
http://www.python.org/community/lists.html for details.


Bug reports
-----------

To report or search for bugs, please use the Python Bug
Tracker at http://sourceforge.net/bugs/?group_id=5470.


Patches and contributions
-------------------------

To submit a patch or other contribution, please use the Python Patch
Manager at http://sourceforge.net/patch/?group_id=5470.  Guidelines
for patch submission may be found at http://www.python.org/patches/.

If you have a proposal to change Python, it's best to submit a Python
Enhancement Proposal (PEP) first.  All current PEPs, as well as
guidelines for submitting a new PEP, are listed at
http://www.python.org/peps/.


Questions
---------

For help, if you can't find it in the manuals or on the web site, it's
best to post to the comp.lang.python or the Python mailing list (see
above).  If you specifically don't want to involve the newsgroup or
mailing list, send questions to [email protected] (a group of volunteers
who answer questions as they can).  The newsgroup is the most
efficient way to ask public questions.


Build instructions
==================

Before you can build Python, you must first configure it.
Fortunately, the configuration and build process has been automated
for Unix and Linux installations, so all you usually have to do is
type a few commands and sit back.  There are some platforms where
things are not quite as smooth; see the platform specific notes below.
If you want to build for multiple platforms sharing the same source
tree, see the section on VPATH below.

Start by running the script "./configure", which determines your
system configuration and creates the Makefile.  (It takes a minute or
two -- please be patient!)  You may want to pass options to the
configure script -- see the section below on configuration options and
variables.  When it's done, you are ready to run make.

To build Python, you normally type "make" in the toplevel directory.
If you have changed the configuration, the Makefile may have to be
rebuilt.  In this case you may have to run make again to correctly
build your desired target.  The interpreter executable is built in the
top level directory.

Once you have built a Python interpreter, see the subsections below on
testing and installation.  If you run into trouble, see the next
section.

Previous versions of Python used a manual configuration process that
involved editing the file Modules/Setup.  While this file still exists
and manual configuration is still supported, it is rarely needed any
more: almost all modules are automatically built as appropriate under
guidance of the setup.py script, which is run by Make after the
interpreter has been built.


Troubleshooting
---------------

See also the platform specific notes in the next section.

If you run into other trouble, see the FAQ
(http://www.python.org/doc/faq) for hints on what can go wrong, and
how to fix it.

If you rerun the configure script with different options, remove all
object files by running "make clean" before rebuilding.  Believe it or
not, "make clean" sometimes helps to clean up other inexplicable
problems as well.  Try it before sending in a bug report!

If the configure script fails or doesn't seem to find things that
should be there, inspect the config.log file.

If you get a warning for every file about the -Olimit option being no
longer supported, you can ignore it.  There's no foolproof way to know
whether this option is needed; all we can do is test whether it is
accepted without error.  On some systems, e.g. older SGI compilers, it
is essential for performance (specifically when compiling ceval.c,
which has more basic blocks than the default limit of 1000).  If the
warning bothers you, edit the Makefile to remove "-Olimit 1500" from
the OPT variable.

If you get failures in test_long, or sys.maxint gets set to -1, you
are probably experiencing compiler bugs, usually related to
optimization.  This is a common problem with some versions of gcc, and
some vendor-supplied compilers, which can sometimes be worked around
by turning off optimization.  Consider switching to stable versions
(gcc 2.95.2, gcc 3.x, or contact your vendor.)

From Python 2.0 onward, all Python C code is ANSI C.  Compiling using
old K&R-C-only compilers is no longer possible.  ANSI C compilers are
available for all modern systems, either in the form of updated
compilers from the vendor, or one of the free compilers (gcc).

Unsupported systems
-------------------

A number of features are not supported in Python 2.5 anymore. Some
support code is still present, but will be removed in Python 2.6. 
If you still need to use current Python versions on these systems,
please send a message to [email protected] indicating that you
volunteer to support this system. For a more detailed discussion 
regarding no-longer-supported and resupporting platforms, as well
as a list of platforms that became or will be unsupported, see PEP 11.

More specifically, the following systems are not supported any
longer:
- SunOS 4
- DYNIX
- dgux
- Minix
- NeXT
- Irix 4 and --with-sgi-dl
- Linux 1
- Systems defining __d6_pthread_create (configure.in)
- Systems defining PY_PTHREAD_D4, PY_PTHREAD_D6,
  or PY_PTHREAD_D7 in thread_pthread.h
- Systems using --with-dl-dld
- Systems using --without-universal-newlines
- MacOS 9

The following systems are still supported in Python 2.5, but
support will be dropped in 2.6:
- Systems using --with-wctype-functions
- Win9x, WinME

Warning on install in Windows 98 and Windows Me
-----------------------------------------------

Following Microsoft's closing of Extended Support for
Windows 98/ME (July 11, 2006), Python 2.6 will stop
supporting these platforms. Python development and
maintainability becomes easier (and more reliable) when
platform specific code targeting OSes with few users
and no dedicated expert developers is taken out. The
vendor also warns that the OS versions listed above
"can expose customers to security risks" and recommends
upgrade.

Platform specific notes
-----------------------

(Some of these may no longer apply.  If you find you can build Python
on these platforms without the special directions mentioned here,
submit a documentation bug report to SourceForge (see Bug Reports
above) so we can remove them!)

GCC 4.1,
GCC 4.2: There is a known incompatibility between Python and GCC,
         where GCC 4.1 and later uses an interpretation of C 
         different to earlier GCC releases in an area where the C 
         specification has undefined behaviour (namely, integer arithmetic 
         involving -sys.maxint-1).

         As a consequence, compiling Python with GCC 4.1/4.2 is not
         recommended. It is likely that this problem will be resolved
         in future Python releases. As a work-around, it seems that
         adding -fwrapv to the compiler options restores the earlier
         GCC behaviour.

Unix platforms: If your vendor still ships (and you still use) Berkeley DB
        1.85 you will need to edit Modules/Setup to build the bsddb185
        module and add a line to sitecustomize.py which makes it the
        default.  In Modules/Setup a line like

            bsddb185 bsddbmodule.c

        should work.  (You may need to add -I, -L or -l flags to direct the
        compiler and linker to your include files and libraries.)

XXX I think this next bit is out of date:

64-bit platforms: The modules audioop, imageop and rgbimg don't work.
        The setup.py script disables them on 64-bit installations.
        Don't try to enable them in the Modules/Setup file.  They
        contain code that is quite wordsize sensitive.  (If you have a
        fix, let us know!)

Solaris: When using Sun's C compiler with threads, at least on Solaris
        2.5.1, you need to add the "-mt" compiler option (the simplest
        way is probably to specify the compiler with this option as
        the "CC" environment variable when running the configure
        script).

        When using GCC on Solaris, beware of binutils 2.13 or GCC
        versions built using it.  This mistakenly enables the
        -zcombreloc option which creates broken shared libraries on
        Solaris.  binutils 2.12 works, and the binutils maintainers
        are aware of the problem.  Binutils 2.13.1 only partially
        fixed things.  It appears that 2.13.2 solves the problem
        completely.  This problem is known to occur with Solaris 2.7
        and 2.8, but may also affect earlier and later versions of the
        OS.

        When the dynamic loader complains about errors finding shared
        libraries, such as

        ld.so.1: ./python: fatal: libstdc++.so.5: open failed:
        No such file or directory

        you need to first make sure that the library is available on
        your system. Then, you need to instruct the dynamic loader how
        to find it. You can choose any of the following strategies:

        1. When compiling Python, set LD_RUN_PATH to the directories
           containing missing libraries.
        2. When running Python, set LD_LIBRARY_PATH to these directories.
        3. Use crle(8) to extend the search path of the loader.
        4. Modify the installed GCC specs file, adding -R options into the
           *link: section.

        The complex object fails to compile on Solaris 10 with gcc 3.4 (at
        least up to 3.4.3).  To work around it, define Py_HUGE_VAL as
        HUGE_VAL(), e.g.:

          make CPPFLAGS='-D"Py_HUGE_VAL=HUGE_VAL()" -I. -I$(srcdir)/Include'
          ./python setup.py CPPFLAGS='-D"Py_HUGE_VAL=HUGE_VAL()"'

Linux:  A problem with threads and fork() was tracked down to a bug in
        the pthreads code in glibc version 2.0.5; glibc version 2.0.7
        solves the problem.  This causes the popen2 test to fail;
        problem and solution reported by Pablo Bleyer.

Red Hat Linux: Red Hat 9 built Python2.2 in UCS-4 mode and hacked
        Tcl to support it. To compile Python2.3 with Tkinter, you will
        need to pass --enable-unicode=ucs4 flag to ./configure.

        There's an executable /usr/bin/python which is Python
        1.5.2 on most older Red Hat installations; several key Red Hat tools
        require this version.  Python 2.1.x may be installed as
        /usr/bin/python2.  The Makefile installs Python as
        /usr/local/bin/python, which may or may not take precedence
        over /usr/bin/python, depending on how you have set up $PATH.

FreeBSD 3.x and probably platforms with NCurses that use libmytinfo or
        similar: When using cursesmodule, the linking is not done in
        the correct order with the defaults.  Remove "-ltermcap" from
        the readline entry in Setup, and use as curses entry: "curses
        cursesmodule.c -lmytinfo -lncurses -ltermcap" - "mytinfo" (so
        called on FreeBSD) should be the name of the auxiliary library
        required on your platform.  Normally, it would be linked
        automatically, but not necessarily in the correct order.

BSDI:   BSDI versions before 4.1 have known problems with threads,
        which can cause strange errors in a number of modules (for
        instance, the 'test_signal' test script will hang forever.)
        Turning off threads (with --with-threads=no) or upgrading to
        BSDI 4.1 solves this problem.

DEC Unix: Run configure with --with-dec-threads, or with
        --with-threads=no if no threads are desired (threads are on by
        default).  When using GCC, it is possible to get an internal
        compiler error if optimization is used.  This was reported for
        GCC 2.7.2.3 on selectmodule.c.  Manually compile the affected
        file without optimization to solve the problem.

DEC Ultrix: compile with GCC to avoid bugs in the native compiler,
        and pass SHELL=/bin/sh5 to Make when installing.

AIX:    A complete overhaul of the shared library support is now in
        place.  See Misc/AIX-NOTES for some notes on how it's done.
        (The optimizer bug reported at this place in previous releases
        has been worked around by a minimal code change.) If you get
        errors about pthread_* functions, during compile or during
        testing, try setting CC to a thread-safe (reentrant) compiler,
        like "cc_r".  For full C++ module support, set CC="xlC_r" (or
        CC="xlC" without thread support).

AIX 5.3: To build a 64-bit version with IBM's compiler, I used the
        following:

        export PATH=/usr/bin:/usr/vacpp/bin
        ./configure --with-gcc="xlc_r -q64" --with-cxx="xlC_r -q64" \
                    --disable-ipv6 AR="ar -X64"
        make

HP-UX:  When using threading, you may have to add -D_REENTRANT to the
        OPT variable in the top-level Makefile; reported by Pat Knight,
        this seems to make a difference (at least for HP-UX 10.20)
        even though pyconfig.h defines it. This seems unnecessary when
        using HP/UX 11 and later - threading seems to work "out of the
        box".

HP-UX ia64: When building on the ia64 (Itanium) platform using HP's
        compiler, some experience has shown that the compiler's
        optimiser produces a completely broken version of python
        (see http://www.python.org/sf/814976). To work around this,
        edit the Makefile and remove -O from the OPT line.

        To build a 64-bit executable on an Itanium 2 system using HP's
        compiler, use these environment variables:

                CC=cc
                CXX=aCC
                BASECFLAGS="+DD64"
                LDFLAGS="+DD64 -lxnet"

        and call configure as:

                ./configure --without-gcc

        then *unset* the environment variables again before running
        make.  (At least one of these flags causes the build to fail
        if it remains set.)  You still have to edit the Makefile and
        remove -O from the OPT line.

HP PA-RISC 2.0: A recent bug report (http://www.python.org/sf/546117)
        suggests that the C compiler in this 64-bit system has bugs
        in the optimizer that break Python.  Compiling without
        optimization solves the problems.

SCO:    The following apply to SCO 3 only; Python builds out of the box
        on SCO 5 (or so we've heard).

        1) Everything works much better if you add -U__STDC__ to the
        defs.  This is because all the SCO header files are broken.
        Anything that isn't mentioned in the C standard is
        conditionally excluded when __STDC__ is defined.

        2) Due to the U.S. export restrictions, SCO broke the crypt
        stuff out into a separate library, libcrypt_i.a so the LIBS
        needed be set to:

                LIBS=' -lsocket -lcrypt_i'

UnixWare: There are known bugs in the math library of the system, as well as
        problems in the handling of threads (calling fork in one
        thread may interrupt system calls in others). Therefore, test_math and
        tests involving threads will fail until those problems are fixed.

QNX:    Chris Herborth ([email protected]) writes:
        configure works best if you use GNU bash; a port is available on
        ftp.qnx.com in /usr/free.  I used the following process to build,
        test and install Python 1.5.x under QNX:

        1) CONFIG_SHELL=/usr/local/bin/bash CC=cc RANLIB=: \
            ./configure --verbose --without-gcc --with-libm=""

        2) edit Modules/Setup to activate everything that makes sense for
           your system... tested here at QNX with the following modules:

                array, audioop, binascii, cPickle, cStringIO, cmath,