如何更新python随附的模块？

Question

I am having trouble with the subprocess module. I am missing the check_output function and I was wondering if there is a way to update/replace this without doing a complete reinstall of python.

Answer 1

Yes, it's possible, you can add the function in yourself if necessary (only suggested if you need it for backwards capability).

if 'check_output' not in dir(subprocess):
    def check_output(cmd_args, *args, **kwargs):
        proc = subprocess.Popen(
            cmd_args, *args,
            stdout=subprocess.PIPE, stderr=subprocess.PIPE, **kwargs)
        out, err = proc.communicate()
        if proc.returncode != 0:
            raise subprocess.CalledProcessError(args)
        return out
    subprocess.check_output = check_output

But as that code shows, you can also just write it a little more verbosely and it doesn't operate any differently.

Edit: Copy directly from subprocess module version Python 2.7

def check_output(*popenargs, **kwargs):
    if 'stdout' in kwargs:
        raise ValueError('stdout argument not allowed, it will be overridden.')
    process = subprocess.Popen(stdout=subprocess.PIPE, *popenargs, **kwargs)
    output, unused_err = process.communicate()
    retcode = process.poll()
    if retcode:
        cmd = kwargs.get("args")
        if cmd is None:
            cmd = popenargs[0]
        raise subprocess.CalledProcessError(retcode, cmd, output=output)
    return output