Keith Dart <[EMAIL PROTECTED]> wrote:
Oh, I forgot to mention that it also has a more user- and programmer-friendly ExitStatus object that processess can return. This is directly testable in Python:
proc = proctools.spawn("somecommand") exitstatus = proc.wait()
if exitstatus: print "good result (errorlevel of zero)" else: print exitstatus # prints message with exit value
This sounds rather like the new subprocess module...
import subprocess rc = subprocess.call(["ls", "-l"])
total 381896 -rw-r--r-- 1 ncw ncw 1542 Oct 12 17:55 1 [snip] -rw-r--r-- 1 ncw ncw 713 Nov 16 08:18 z~
print rc
0
But this evaluates to False in Python, but True in a shell. It also requires an extra check for normal exit, or exit by a signal. The proctools ExitStatus object avaluates to True only on a normal exit, period. Thus it follows a shell semantics for clarity. You cannot do this with the subprocess module:
if rc:
print "exited normally"But in proctools, the exitstatus is an object that evaluates True only for normal exit.
import proctools
proc = proctools.spawnpipe("ls -l")
print proc.read()
....
print proc.exitstatus
ls: Exited normally.
proc = proctools.spawnpipe("ls -l xx") print proc.read() 'ls: xx: No such file or directory\n'
print proc.exitstatus ls: Exited abnormally with status 1.
if proc.exitstatus:
print "returned normally"
But you can get the integer return value, if you want it, like this: int(proc.exitstatus)
or query it with methods returning booleans:
exitstatus.exited() exitstatus.signalled() exitstatus.stopped()
Also, proctools lets you use a pty, if you choose. Not every program works well from a pipe.
IMHO the new subprocess module is a very well thought out interface...
The proctools Process object presents a file-like object to the rest of Python, which makes a process polymorhic with any other file, pipe or socket object. It has the usual read, write, readline, and readlines methods. It can also be made non-blocking, and you can have many open at once. In addition, there are special methods for controlling the sub-process: You can kill it, stop it, re-start it, clone it, wait on it, and get stats from it. The stat() method returns a ProcStat object, which has attributes like what you get from the 'ps' program. Need to know the process's RSS? No problem. It also supports logging to a log file, and on-exit callback for persistent process requirements.
You always invoke the spawn* functions with a string. This is parsed by a shell-like parser (the shparser module that comes with it), but no /bin/sh is invoked. The parser can handle single and double quotes, and backslash escapes.
Alas, one thing the proctools module does not do well yet is create a pipeline. I have plans to fix that.
It does not work with MS Windows, but can work with cygwin on Windows.
Whew... and I have not even covered the ProcessManager object...
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