On Sun, 29 Jan 2023 at 14:29, Jach Feng <jf...@ms4.hinet.net> wrote: > Thank you for detail explanation of the role the shell is involved in this > problem. I'm very appreciated! > > It seems that a CLI app may become very complex when dealing with different > kind of shell, and may not be possible to solve its problem. But the good > thing in my app is that I need only to handle math equation:-) > > > So why so much objection to explaining the need for "--"? > Because of using " to enclose a space separated string is a common > convention, and adding a "--" is not:-)
Double hyphen is incredibly common. On most Unix shells, double quotes are just one way of marking that a space should be included in an argument rather than separating (others include single quotes, escaping the space with a backslash, and changing the field separator). Of course, everything is conventions, not requirements, but it's generally better to let the person's shell define the argument splitting; that way, if your script is called from another process, it's dead easy to control the splitting yourself (just pass an array/list of arguments to the subprocess spawner). Maybe you come from Windows, where there are fewer conventions and less shell parsing, but argparse follows Unix conventions, so if you don't want Unix conventions, don't use argparse. Just read sys.argv directly. ChrisA -- https://mail.python.org/mailman/listinfo/python-list
