[Tutor] subprocess.call warning

Norman Khine norman at khine.net
Mon Oct 4 08:42:16 CEST 2010

thank you for the reply

On Mon, Oct 4, 2010 at 12:47 AM, Steven D'Aprano <steve at pearwood.info> wrote:
> On Mon, 4 Oct 2010 06:44:54 am Norman Khine wrote:
>> hello, from the docs http://docs.python.org/library/subprocess.html i
>> see there is a WARNING about deadlock when using the subprocess.call.
>> in my code i have this
>> http://pastie.org/1197024
> The warning says:
>    Like Popen.wait(), this will deadlock when using stdout=PIPE
>    and/or stderr=PIPE and the child process generates enough
>    output to a pipe such that it blocks waiting for the OS pipe
>    buffer to accept more data.
> Since you don't set either stdout or stderr to PIPE, you shouldn't have
> to worry about a deadlock.
ah ok
>> the first calls the 'sox' library which joins all the .wav files into
>> one file and then i use the 'wav2swf' library to create a SWF output
>> of the file.
>> can the code be improved?
> Code can always be improved :-) What do you consider an improvement?
> Easy to maintain in the future? Faster? Smaller?

to make it faster.

> What does get_abspath do? It sounds like it *may* be your own version of
> os.path.abspath.

i am using the iTools python library


> I'm not sure why you have a list called "imgtext" that doesn't contain
> text. It seems to be a list of partial file names rather than "image
> text".

the code is for my own implementation of a captcha to see how python
interacts with system libraries such as SOX and WAV2SWF and of course
to learn.


but yes, it is 'text' so i will change it in the next version.

> Your code, as given, can't work, because you call isupper() on integers
> 1 2 and 3. That will fail.
> I'd probably prefer to generate the filenames differently:
> def fix_filename(fname, base=sound_path):
>    fname = str(fname)
>    if fname.isupper():
>        fname = "upper_%s" % fname.lower()
>    return os.path.join(base, fname + '.wav')
> and then call it:
> filenames = ['A', 'b', 'c', 'D', 1, 2, 3]
> for name in filenames:
>    name = fix_filename(name)
>    sox_filenames.append(name)
> --
> Steven D'Aprano
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