[Tutor] how to make a script do two things at once.

[I-McTaggart, Peter]

You might also try the following from the os module. (taken from the
Python manuals.)

This may be easier than getting your head around threads.

-----------------------------
spawnl( mode, path, ...) 

spawnle( mode, path, ..., env) 

spawnlp( mode, file, ...) 

spawnlpe( mode, file, ..., env) 

spawnv( mode, path, args) 

spawnve( mode, path, args, env) 

spawnvp( mode, file, args) 

spawnvpe( mode, file, args, env) 

Execute the program path in a new process. If mode is P_NOWAIT, this
function returns the process ID of the new process; if mode is P_WAIT,
returns the process's exit code if it exits normally, or -signal, where
signal is the signal that killed the process. On Windows, the process ID
will actually be the process handle, so can be used with the waitpid()
function. 

[...snip...]

As an example, the following calls to spawnlp() and spawnvpe() are
equivalent: 

import os
os.spawnlp(os.P_WAIT, 'cp', 'cp', 'index.html', '/dev/null')

L = ['cp', 'index.html', '/dev/null']
os.spawnvpe(os.P_WAIT, 'cp', L, os.environ)

Availability: Unix, Windows. spawnlp(), spawnlpe(), spawnvp() and
spawnvpe() are not available on Windows. New in version 1.6. 



> -----Original Message-----
> From: nephish [mailto:nephish at xit.net] 
> Sent: 22 August 2005 1:23 
> To: Kent Johnson
> Cc: tutor at python.org
> Subject: Re: [Tutor] how to make a script do two things at once.
> 
> 
> Kent Johnson wrote:
> 
> >nephish wrote:
> >  
> >
> >>Hey there,
> >>i have a simple question about getting a script to do
> >>two things at once.
> >>like this.
> >>
> >>
> >>for i in range(100):
> >>    print i
> >>    time.sleep(.2)
> >>    if i == 15:
> >>        os.system('python /home/me/ipupdate.py')
> >>       
> >>print 'done'
> >>
> >>when i run this, it stops at 15 and runs the script called 
> out in the
> >>os.system line. i know it is supposed to do that. But, how 
> could i get a 
> >>script to do this without stopping the count (or delaying 
> it unill the 
> >>script called exits) 
> >>    
> >>
> >
> >One way to get a script to do two things 'at once' is to use 
> threads. 
> >Threads are also a good way to introduce strange bugs into 
> your program 
> >so you should do some reading about them. I can't find a good 
> >introduction - anyone else have a suggestion? Here is a brief one: 
> >http://www.wellho.net/solutions/python-python-threads-a-first
-example.h
>tml
>
>Here are a couple of articles, not really introductory: 
>http://linuxgazette.net/107/pai.html
>http://www.devshed.com/c/a/Python/Basic-Threading-in-Python/
>
>Anyway here is something to get you started, this version of your 
>program starts a new thread to do the os.system call, that way the main

>thread doesn't block.
>
>import os, threading, time
>
>def doSomething():
>    ''' This function will be called from the second thread '''
>    os.system('''python -c "from time import sleep;sleep(2);print 
>'hello'"''')
>    
>for i in range(30):
>    print i
>    time.sleep(.2)
>    if i == 10:
>        print 'Starting thread'
>        threading.Thread(target=doSomething).start()
>       
>print 'done'
>
>Kent
>
>_______________________________________________
>Tutor maillist  -  Tutor at python.org 
>http://mail.python.org/mailman/listinfo/tutor
>
>  
>
thanks for all of the responses, yep, looks like threads is what i want 
to go with. got the docs you guys linked me to bookmarked. this is going

to take a bit of research.
thanks again for showing me where to start.
shawn
_______________________________________________
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