1 IBM VisualAge C/C++ for OS/2

     2 ============================

     3 

     4 To build Python for OS/2, change into ./os2vacpp and issue an 'NMAKE'

     5 command.  This will build a PYTHON15.DLL containing the set of Python

     6 modules listed in config.c and a small PYTHON.EXE to start the

     7 interpreter.

     8 

     9 By changing the C compiler flag /Gd- in the makefile to /Gd+, you can

    10 reduce the size of these by causing Python to dynamically link to the

    11 C runtime DLLs instead of including their bulk in your binaries. 

    12 However, this means that any system on which you run Python must have

    13 the VAC++ compiler installed in order to have those DLLs available.

    14 

    15 During the build process you may see a couple of harmless warnings:

    16 

    17   From the C Compiler, "No function prototype given for XXX", which

    18   comes from the use of K&R parameters within Python for portability.

    19 

    20   From the ILIB librarian, "Module Not Found (XXX)", which comes

    21   from its attempt to perform the (-+) operation, which removes and

    22   then adds a .OBJ to the library.  The first time a build is done,

    23   it obviously cannot remove what is not yet built.

    24 

    25 This build includes support for most Python functionality as well as

    26 TCP/IP sockets.  It omits the Posix ability to 'fork' a process but

    27 supports threads using OS/2 native capabilities.  I have tried to

    28 support everything possible but here are a few usage notes.

    29 

    30 

    31 -- os.popen() Usage Warnings

    32 

    33 With respect to my implementation of popen() under OS/2:

    34 

    35     import os

    36 

    37     fd = os.popen("pkzip.exe -@ junk.zip", 'wb')

    38     fd.write("file1.txt\n")

    39     fd.write("file2.txt\n")

    40     fd.write("file3.txt\n")

    41     fd.write("\x1a")  # Should Not Be Necessary But Is

    42     fd.close()

    43 

    44 There is a bug, either in the VAC++ compiler or OS/2 itself, where the

    45 simple closure of the write-side of a pipe -to- a process does not

    46 send an EOF to that process.  I find I must explicitly write a

    47 control-Z (EOF) before closing the pipe.  This is not a problem when

    48 using popen() in read mode.

    49 

    50 One other slight difference with my popen() is that I return None

    51 from the close(), instead of the Unix convention of the return code

    52 of the spawned program.  I could find no easy way to do this under

    53 OS/2.

    54 

    55 

    56 -- BEGINLIBPATH/ENDLIBPATH

    57 

    58 With respect to environment variables, this OS/2 port supports the

    59 special-to-OS/2 magic names of 'BEGINLIBPATH' and 'ENDLIBPATH' to

    60 control where to load conventional DLLs from.  Those names are

    61 intercepted and converted to calls on the OS/2 kernel APIs and

    62 are inherited by child processes, whether Python-based or not.

    63 

    64 A few new attributes have been added to the os module:

    65 

    66     os.meminstalled  # Count of Bytes of RAM Installed on Machine

    67     os.memkernel     # Count of Bytes of RAM Reserved (Non-Swappable)

    68     os.memvirtual    # Count of Bytes of Virtual RAM Possible

    69     os.timeslice     # Duration of Scheduler Timeslice, in Milliseconds

    70     os.maxpathlen    # Maximum Length of a Path Specification, in chars

    71     os.maxnamelen    # Maximum Length of a Single Dir/File Name, in chars

    72     os.version       # Version of OS/2 Being Run e.g. "4.00"

    73     os.revision      # Revision of OS/2 Being Run (usually zero)

    74     os.bootdrive     # Drive that System Booted From e.g. "C:"

    75                      # (useful to find the CONFIG.SYS used to boot with)

    76 

    77 

    78 -- Using Python as the Default OS/2 Batch Language

    79 

    80 Note that OS/2 supports the Unix technique of putting the special

    81 comment line at the time of scripts e.g. "#!/usr/bin/python" in

    82 a different syntactic form.  To do this, put your script into a file

    83 with a .CMD extension and added 'extproc' to the top as follows:

    84 

    85     extproc C:\Python\Python.exe -x

    86     import os

    87     print "Hello from Python"

    88 

    89 The '-x' option tells Python to skip the first line of the file

    90 while processing the rest as normal Python source.

    91 

    92 

    93 -- Suggested Environment Variable Setup

    94 

    95 With respect to the environment variables for Python, I use the

    96 following setup:

    97 

    98     Set PYTHONHOME=E:\Tau\Projects\Python;D:\DLLs

    99     Set PYTHONPATH=.;E:\Tau\Projects\Python\Lib; \

   100                      E:\Tau\Projects\Python\Lib\plat-win

   101 

   102 The EXEC_PREFIX (optional second pathspec on PYTHONHOME) is where

   103 you put any Python extension DLLs you may create/obtain.  There

   104 are none provided with this release.

   105 

   106 

   107 -- Contact Info

   108 

   109 Jeff Rush is no longer supporting the VACPP port :-(

   110 

   111 I don't have the VACPP compiler, so can't reliably maintain this port. 

   112 

   113 Anyone with VACPP who can contribute patches to keep this port buildable

   114 should upload them to the Python Patch Manager at Sourceforge and 

   115 assign them to me for review/checkin.

   116 

   117 Andrew MacIntyre

   118 aimacintyre at users.sourceforge.net

   119 August 18, 2002.