Interesting list Validity (True/False)

[nufuhsus at gmail.com]

 On May 11, 2:28 pm, nufuh... at gmail.com wrote:
>
>
>
>
>
> > Hello all,
>
> > First let me appologise if this has been answered but I could not find
> > an acurate answer to this interesting problem.
>
> > If the following is true:
> >     C:\Python25\rg.py>python
> >     Python 2.5.1 (r251:54863, Apr 18 2007, 08:51:08) [MSC v.1310 32
> > bit (Intel)] on
> >     win32
> >     Type "help", "copyright", "credits" or "license" for more
> > information.
> >     >>> [] == []
> >     True
> >     >>> ['-o'] == []
> >     False
> >     >>> ['-o'] == False
> >     False
>
> > Then why do I get the following results:
> >     C:\Python25\rg.py>help.py -o
> >     print arg ['-o']
> >     type(arg): <type 'list'>
> >     arg is True? False
> >         help.py version 1.0 Copyright RDEG (c) 2007
> >         ['-o'] is an unrecognized option.
> >         Progam Exit (0)
>
> > <python>
> >     import sys
>
> >     _ver_ = 1.00
>
> >     if '-h' in sys.argv or '--help' in sys.argv:
> >         print
> >         print "    help.py Version", _ver_, "Copyright RDEG (c) 2007"
> >         print '''
>
> >         Options : -h, --help -- display this message
> >             Progam Exit (0)'''
> >         sys.exit(0)
> >     else:
> >         arg = sys.argv[1:]
> >         print 'print arg', arg
> >         print 'type(arg):', type(arg)
> >         print 'arg is True?', arg == True
> >         print "    help.py version", _ver_, "Copyright RDEG (c) 2007"
> >         print "    ", arg, "is an unrecognized option."
> >         print "    Progam Exit (0)"
> >         sys.exit(0)
> > </python>
>


I hope this helps (I have tried to post this twice already but it
seems to be going somewhere else) you help me.

What I would like to happen is:
    else:
        arg = sys.argv[1:]
        print 'print arg', arg
        print 'type(arg):', type(arg)
        print 'arg is True?', arg == True
        if arg != True:
            print "    No Option Provided"
        print "    help.py version", _ver_, "Copyright RDEG (c) 2007"
        print "    ", arg, "is an unrecognized option."
        print "    Progam Exit (0)"
        sys.exit(0)

But as you can see by my output ['-o'] seems to be False as well as []
so the if happens regardless.

According to the "Book", ['-o'] should return True which should fail
the if, no?