How to check if fileinput is empty? Python

Question

I have created a Python program which runs from command line, the user inputs files for processing. The files are read in from fileinput, and optparse options can be used on them. My problem is that if the user does not input any option or file name, the program does nothing and continues running. I want the program to display the help options by default if fileinput is empty.

Is there a way to check to see if fileinput.input(argv) is empty? It defaults to stdin when empty, but how can I check if it is empty beforehand?

def parse_options():
    parser = optparse.OptionParser()
    parser.add_option('-o', '--output', dest='output',
                      default='c',
                      help='[c/f/h] output to (c)onsole, (f)ile or (h)tml')
    parser.add_option('-s', '--sort', dest='sort',
                      default='pa',
                      help='[p/c/m/d] sort by (p)ath, (c)all frequency, (m)ean duration or (d)uration,\n'
                           '[a/d] sort by (a)scending or (d)escending order')

    options, argv = parser.parse_args()

    if options.output == 'f':
        output_action = LogAnalyser.output_to_file
    elif options.output == 'h':
        output_action = LogAnalyser.output_to_html
    else:
        output_action = LogAnalyser.output_to_console

    #if fileinput.input(argv) is None:
    #    parser.print_help()
    #    quit()

    return output_action, options.sort, fileinput.input(argv)

perror · Accepted Answer · 2016-12-19 17:51:18Z

1

Well, if optparse parser returns a positional argument list, you can simply check it for emptiness:

(options, args) = parser.parse_args()
...
if args:
    for line in fileinput.input(args):
        ...

If this isn't enough, please elaborate your question.

edited Dec 19, 2016 at 17:51

perror

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answered Jul 24, 2014 at 10:00

Netch

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5 Comments

user3075082 Over a year ago

I want the user to be able to use the program just by entering file names as well, so they may not always use an options argument. Sorry I did not make this clear.

Netch Over a year ago

Where do you want to enter file names?

user3075082 Over a year ago

At command line, I would like it to be python scriptname.py file1.txt file2.txt with possible options like -o f

Netch Over a year ago

This is as exactly it will be after optparse processing. Do you really call it?

user3075082 Over a year ago

Okay, I understand you now, sorry about that.

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