Python argparse: Force a list item to be unique

Question

Being able to validate the list items using choices=servers below is nice.

servers = [ \"ApaServer\", \"BananServer\", \"GulServer\", \"SolServ         


        

Answer 1

I don't think, that you can enforce this with argparse, but I also don't see any reason to do so. Just document in help that duplicates are ignored. If the user passes duplicate arguments to --only, just let her do so, and ignore the duplicate argument when processing the option arguments (e.g. by turing the list into a set() before processing).