IBM VisualAge C/C++ for OS/2 | |
============================ | |
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 | |
If you have questions, suggestions or problems specifically with | |
the OS/2 VAC++ port of Python, please contact me at: | |
Jeff Rush <jrush@summit-research.com>. | |
I support no other platform but OS/2 (and eventually AmigaDOS). |