proposal: Optional command parameter rework

[AndreasHGK]

There is currently a limitation to how optional commands are done: you cant be sure whether a parameter was provided or that the user just gave the null value as an argument.

This is not unfixable, and I believe something similar to rust's Option<> type might be a way to solve this.
I have already implemented something like this in a library of my own: https://github.com/AndreasHGK/go-interactions and, while not the cleanest implementation, it does seem to work.

A command with an optional parameter would look like this:

type MyCommand struct {
    RequiredParam string
    OptionalParam cmd.Optional[string]
}

func (m MyCommand) Run(...) {
    optionalString, ok := m.OptionalParam.Read()
    alsoOptionalString := m.OptionalParam.ReadOrDefault("this is a default string")
}

Even if this is implemented, the old way of doing commands could technically still be supported but I am not sure if that is such a good idea, and DF is in alpha anyway.

[Sandertv]

Closed in 92477eb.