On 2023-01-22 at 18:19:13 -0800, Jach Feng <jf...@ms4.hinet.net> wrote:
> 1) Modify the sys.argv by inserting an item '--' before parsing it, ie. > sys.argv.insert(1, '--') > args = parser.parse_args() Please don't do that. :-) In my mind, sys.argv belongs to Python, not the application. Instead, pass a newly created argument list to parse_args: args = parser.parse_args(['--'] + sys.argv) This approach (adjusting the actual arguments) will work until your program actually has options. > 2) By adding an extra space character before the leading '-' sign, ie. > e:\Works\Python>py infix2postfix.py " -4^2+5.3*abs(-2-1)/2" > -4 2 ^ 5.3 -2 1 - abs * 2 / + > > But no idea how it works? and if it can survive in a newer argparse > version?:-) It works because argparse checks the first character of each argument, and *doesn't* strip/trim whitespace. So "-x" looks like an option, and " -x" looks an argument. -- https://mail.python.org/mailman/listinfo/python-list
