A little disappointed so far

[Duncan Booth]

Graham Nicholls <graham at rockcons.co.uk> wrote in 
news:bg3ya.4397$573.2228 at news-binary.blueyonder.co.uk:

> How do I then handle the -o [filename case]  I hate the idea of an
> "ignore_this_word" flag for the next time around the loop.

You had:
        i=0
        while (i < argc):
                opt=arglist[i]
                ...
                i += 1

Since you want to be able to pull out another argument, you want to iterate 
over the list, but use an explicit iterator.

       argiter = iter(arglist)
       for opt in argiter:
           if opt == '-o':
               try:
                   filename = argiter.next()
               except StopIteration:
                   error("-o requires another argument")

You could also handle the exception outside the for loop, as it could be 
thrown for any option that needed an extra argument. Of course you really 
should write this all in a more object-oriented manner, because it will be 
cleaner and easier to maintain. It you don't want to use any of Python's 
existing ways of processing arguments you could roll your own. Something 
like this perhaps (untested code, so it undoubtedly has typos):


class Args:
    def __init__(self, arglist):
        self.debug = self.verbose = False
        self.outfile = None
        self.flist = []

        argiter = iter(arglist)
        self.progname = argiter.next()

        for opt in argiter:
            if opt.startswith('-'):
                handler = 'opt_' + opt[1]
                handlerfn = getattr(self, handler, badOption)
                try:
                    handlerfn(opt, argiter)
                except StopIteration:
                    usage("Option %s expected another argument" % opt)
                    sys.exit(BAD_ARGS)
            else:
                self.notAnOption(opt)

    def opt_d(self, opt, argiter):
        print "%s DEBUG - debug activated" % progname
        self.debug=True

    def opt_v(self, opt, argiter):
        self.verbose=True
        print "%s version %s" % (progname,version)

    def opt_o(self, opt, argiter):
        self.outfile = argiter.next()
        if outfile.startswith('-'):
                raise StopIteration
    
    def badOption(self, opt, argiter):
        usage("Unknown option %s" % opt)
        sys.exit(BAD_ARGS)

    def notAnOption(self, arg):
        self.flist.append(arg)

and then the rest of your code does:

    args = Args(sys.argv)
    infiles, outfile = args.flist, args.outfile
    ... etc.

-- 
Duncan Booth                                             duncan at rcp.co.uk
int month(char *p){return(124864/((p[0]+p[1]-p[2]&0x1f)+1)%12)["\5\x8\3"
"\6\7\xb\1\x9\xa\2\0\4"];} // Who said my code was obscure?