Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.lang.python > #52344 > unrolled thread

Re: Am I not seeing the Error?

Back to article view | Back to comp.lang.python

This discussion starts older than the indexed window; earlier articles aren't shown. The article labeled Started by below is the oldest one visible, not the original post.

Contents

  Re: Am I not seeing the Error? Chris Angelico <rosuav@gmail.com> - 2013-08-11 03:33 +0100
    Re: Am I not seeing the Error? Roy Smith <roy@panix.com> - 2013-08-10 22:43 -0400
      Re: Am I not seeing the Error? Chris Angelico <rosuav@gmail.com> - 2013-08-11 03:47 +0100
      Re: Am I not seeing the Error? Devyn Collier Johnson <devyncjohnson@gmail.com> - 2013-08-12 08:33 -0400
      Re: Am I not seeing the Error? Zachary Ware <zachary.ware+pylist@gmail.com> - 2013-08-12 08:20 -0500
      Re: Am I not seeing the Error? Ned Batchelder <ned@nedbatchelder.com> - 2013-08-12 10:01 -0400
      Re: Am I not seeing the Error? Devyn Collier Johnson <devyncjohnson@gmail.com> - 2013-08-12 10:04 -0400
        Re: Am I not seeing the Error? Roy Smith <roy@panix.com> - 2013-08-12 11:47 -0400
          Re: Am I not seeing the Error? Joel Goldstick <joel.goldstick@gmail.com> - 2013-08-12 12:56 -0400
          Re: Am I not seeing the Error? Chris Angelico <rosuav@gmail.com> - 2013-08-12 18:19 +0100
          Re: Am I not seeing the Error? Devyn Collier Johnson <devyncjohnson@gmail.com> - 2013-08-12 16:16 -0400
          Re: Am I not seeing the Error? Joel Goldstick <joel.goldstick@gmail.com> - 2013-08-12 16:34 -0400
          Re: Am I not seeing the Error? Ned Batchelder <ned@nedbatchelder.com> - 2013-08-12 16:35 -0400
          Re: Am I not seeing the Error? Joshua Landau <joshua@landau.ws> - 2013-08-13 09:19 +0100
            Re: Am I not seeing the Error? Steven D'Aprano <steve@pearwood.info> - 2013-08-13 08:50 +0000
              Re: Am I not seeing the Error? Devyn Collier Johnson <devyncjohnson@gmail.com> - 2013-08-13 06:31 -0400
              Re: Am I not seeing the Error? Robert Kern <robert.kern@gmail.com> - 2013-08-13 13:11 +0100
              Re: Am I not seeing the Error? Terry Reedy <tjreedy@udel.edu> - 2013-08-13 12:12 -0400
              Re: Am I not seeing the Error? Michael Torrie <torriem@gmail.com> - 2013-08-13 19:55 -0600
            Re: Am I not seeing the Error? Grant Edwards <invalid@invalid.invalid> - 2013-08-13 13:55 +0000
      Re: Am I not seeing the Error? Zachary Ware <zachary.ware+pylist@gmail.com> - 2013-08-12 10:37 -0500
      Re: Am I not seeing the Error? Zachary Ware <zachary.ware+pylist@gmail.com> - 2013-08-12 10:47 -0500
    Re: Am I not seeing the Error? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-08-11 08:28 +0000
      Re: Am I not seeing the Error? Joshua Landau <joshua@landau.ws> - 2013-08-11 11:18 +0100
      Re: Am I not seeing the Error? Roy Smith <roy@panix.com> - 2013-08-11 09:27 -0400

Page 2 of 2 — ← Prev page 1 [2]

#52419

On Mon, Aug 12, 2013 at 9:04 AM, Devyn Collier Johnson
<devyncjohnson@gmail.com> wrote:
>
> Zachary, are you, Ned, and Terry trying to say the syntax should be
>
> job = multiprocessing.Process(func1(), func2())
>
> not
>
> job = multiprocessing.Process(func1(); func2())
>

Basically, yes.  The first option there is equivalent to this:

    func_returns = (func1(), func2())

    job = multiprocessing.Process(*func_returns)

The second option is equivalent to this:

    job = multiprocessing.Process(func1()

    func2())

...which is actually several different syntax errors, depending on how
you look at it.  Semi-colon is only ever used in Python as a
substitute for \n-plus-some-spaces.  And, since in your original
example, your semi-colons are inside parenthesis, they really have no
effect at all due to implicit line continuation within parens.  So
your original line:

JOB_WRITEURGFILES =
multiprocessing.Process(write2file('./mem/ENGINE_PID', ENGINEPID);
write2file(SENTEMPPATH, ''); write2file(INPUTMEM, ''));
JOB_WRITEURGFILES.start()

is really:

    JOB_WRITEURGFILES =
multiprocessing.Process(write2file('./mem/ENGINE_PID', ENGINEPID)
write2file(SENTEMPPATH, '') write2file(INPUTMEM, ''))

    JOB_WRITEURGFILES.start()

It should be obvious now that the syntax error comes from not
separating the arguments to Process.

Trying to read between the lines a little here, I don't think you have
quite figured out how multiprocessing.Process works; that first option
above will only work if func1 returns None and func2 returns a
callable object and the second has no hope.  I think this is more
along the lines of what you're really after:

    def process_func():
        func1()
        func2()

    if __name__ == '__main__':
        job = multiprocessing.Process(target=process_func) # note: no
() after process_func!
        job.start()

I'd suggest giving the multiprocessing.Process docs [0] a good
read-through.  Keep in mind that Process is just a type like any other
(str, int, list, etc.), and calling its constructor is subject to the
same rules as any other function call.


-- 
Zach

[0] http://docs.python.org/3/library/multiprocessing#the-process-class

[toc] | [prev] | [next] | [standalone]

#52421

On Mon, Aug 12, 2013 at 10:37 AM, Zachary Ware
<zachary.ware+pylist@gmail.com> wrote:
> [snip my last reply with a few code samples]

My apologies for Gmail's mangling of my samples.  Any code that is not
indented should be on the previous line.

-- 
Zach

[toc] | [prev] | [next] | [standalone]

#52368

On Sun, 11 Aug 2013 03:33:52 +0100, Chris Angelico wrote:

> Next thing to do is split it into more lines. Why is all that in a
> single line?

The only good excuse for writing multiple statements on a single line 
separated by semi-colons is if the Enter key on your keyboard is broken.


:-)


-- 
Steven

[toc] | [prev] | [next] | [standalone]

#52378

On 11 August 2013 09:28, Steven D'Aprano
<steve+comp.lang.python@pearwood.info> wrote:
> into more lines. Why is all that in a
>> single line?
>
> The only good excuse for writing multiple statements on a single line
> separated by semi-colons is if the Enter key on your keyboard is broken.

That's not a good excuse.

It *is* a good excuse for any of the following:

* Buying a new keyboard
* Using a new keymap, possibly replacing cAPSLOCK with Return
* Crying

[toc] | [prev] | [next] | [standalone]

#52387

In article <52074b43$0$30000$c3e8da3$5496439d@news.astraweb.com>,
 Steven D'Aprano <steve+comp.lang.python@pearwood.info> wrote:

> On Sun, 11 Aug 2013 03:33:52 +0100, Chris Angelico wrote:
> 
> > Next thing to do is split it into more lines. Why is all that in a
> > single line?
> 
> The only good excuse for writing multiple statements on a single line 
> separated by semi-colons is if the Enter key on your keyboard is broken.

Well, maybe if you're testing something on the command line with "python 
-c".

[toc] | [prev] | [standalone]

Page 2 of 2 — ← Prev page 1 [2]

Back to top | Article view | comp.lang.python

csiph-web