CWE-ou-minkata/SDKs/XPlatform/Cypython-2.3.3/PC/os2vacpp

IBM VisualAge C/C++ for OS/2

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

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

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

interpreter.



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

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

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

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

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



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



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

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



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

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

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

  it obviously cannot remove what is not yet built.



This build includes support for most Python functionality as well as

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

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

support everything possible but here are a few usage notes.





-- os.popen() Usage Warnings



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



    import os



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

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

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

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

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

    fd.close()



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

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

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

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

using popen() in read mode.



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

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

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

OS/2.





-- BEGINLIBPATH/ENDLIBPATH



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

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

control where to load conventional DLLs from.  Those names are

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

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



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



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

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

    os.memvirtual    # Count of Bytes of Virtual RAM Possible

    os.timeslice     # Duration of Scheduler Timeslice, in Milliseconds

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

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

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

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

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

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





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



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

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

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

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



    extproc C:\Python\Python.exe -x

    import os

    print "Hello from Python"



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

while processing the rest as normal Python source.





-- Suggested Environment Variable Setup



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

following setup:



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

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

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



The EXEC_PREFIX (optional second pathspec on PYTHONHOME) is where

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

are none provided with this release.





-- Contact Info



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



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



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

should upload them to the Python Patch Manager at Sourceforge and 

assign them to me for review/checkin.



Andrew MacIntyre

aimacintyre at users.sourceforge.net

August 18, 2002.