achieving an optional flag

[Cry-Tokyo]

i was wondering if there was a similar way to how other cli parsers can provide this functionality

bin https://google.com https://google.com
bin -l https://google.com https://google.com
bin --links https://google.com https://google.com

and in code get a Vec

[epage]

It would help if this would more explicit in what is intended.

For example, do you mean

$ bin https://duckduckgo.com https://google.com
$ bin -lhttps://duckduckgo.com https://google.com
$ bin --links=https://duckduckgo.com https://google.com

translates to

links = [
    "https://duckduckgo.com",
    "https://google.com",
]

[epage]

a similar way to how other cli parsers can provide this functionality

Would also help to understand this by providing context on what you are referring to here.

[epage]

So based on my rendition of the example,

For us, options and positionals are distinct and we don't allow them to write to the same destination (#3146).

This can be modeled with a separate option and positional and then merging them together manually. This does get more complicated if you intend for the placement of --links to be significant to the ordering of the Vec (the Vec order changes based on whether --links comes before or after the positional argument). We do track relative position of values but do not expose it in the derive API, only the builder API.