readme.txt
1IBM VisualAge C/C++ for OS/2
2============================
3
4To build Python for OS/2, change into ./os2vacpp and issue an 'NMAKE'
5command. This will build a PYTHON15.DLL containing the set of Python
6modules listed in config.c and a small PYTHON.EXE to start the
7interpreter.
8
9By changing the C compiler flag /Gd- in the makefile to /Gd+, you can
10reduce the size of these by causing Python to dynamically link to the
11C runtime DLLs instead of including their bulk in your binaries.
12However, this means that any system on which you run Python must have
13the VAC++ compiler installed in order to have those DLLs available.
14
15During 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
25This build includes support for most Python functionality as well as
26TCP/IP sockets. It omits the Posix ability to 'fork' a process but
27supports threads using OS/2 native capabilities. I have tried to
28support everything possible but here are a few usage notes.
29
30
31-- os.popen() Usage Warnings
32
33With 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
44There is a bug, either in the VAC++ compiler or OS/2 itself, where the
45simple closure of the write-side of a pipe -to- a process does not
46send an EOF to that process. I find I must explicitly write a
47control-Z (EOF) before closing the pipe. This is not a problem when
48using popen() in read mode.
49
50One other slight difference with my popen() is that I return None
51from the close(), instead of the Unix convention of the return code
52of the spawned program. I could find no easy way to do this under
53OS/2.
54
55
56-- BEGINLIBPATH/ENDLIBPATH
57
58With respect to environment variables, this OS/2 port supports the
59special-to-OS/2 magic names of 'BEGINLIBPATH' and 'ENDLIBPATH' to
60control where to load conventional DLLs from. Those names are
61intercepted and converted to calls on the OS/2 kernel APIs and
62are inherited by child processes, whether Python-based or not.
63
64A 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
80Note that OS/2 supports the Unix technique of putting the special
81comment line at the time of scripts e.g. "#!/usr/bin/python" in
82a different syntactic form. To do this, put your script into a file
83with 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
89The '-x' option tells Python to skip the first line of the file
90while processing the rest as normal Python source.
91
92
93-- Suggested Environment Variable Setup
94
95With respect to the environment variables for Python, I use the
96following 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
102The EXEC_PREFIX (optional second pathspec on PYTHONHOME) is where
103you put any Python extension DLLs you may create/obtain. There
104are none provided with this release.
105
106
107-- Contact Info
108
109Jeff Rush is no longer supporting the VACPP port :-(
110
111I don't have the VACPP compiler, so can't reliably maintain this port.
112
113Anyone with VACPP who can contribute patches to keep this port buildable
114should upload them to the Python Patch Manager at Sourceforge and
115assign them to me for review/checkin.
116
117Andrew MacIntyre
118aimacintyre at users.sourceforge.net
119August 18, 2002.
120