Parse nested sctructs about go-arg

[alexflint]

Yes I'm open to this. Perhaps using a special prefix tag, like this:

type DBArgs struct {
  User string
  Password string
}

var args struct {
  DB DBArgs `arg:"db."`
}

Note that the prefix includes the dot ".", so you could also do "db-" if you prefer namespacing via hyphens.

As @aspcartman mentioned, this should not break the existing behavior of nested structs, which is to default to no prefix.

[aspcartman]

I like the idea, but that will collide with the existing logic for the embedded structs (see the Readme.md) and either become inconsistent:

var args struct {
	DB1 struct {
		User		string
		Password	string
	}
	DB2 struct {
		User		string
		Password	string
	}
}

$ app --user guest # where would "guest" end up?

or break backwards compatibility and require a major version.

May that be solved by a special tag?

[SergeAx]

@aspcartman

Currently using structs in go-arg is like this:

type DbArgs struct {
	User	string
	Password string
}

type LogArgs struct {
	Enable	bool
	Level	string
}

var args struct {
	DbArgs
	LogArgs
}

As you can see, it's kinda anonymous (not named).

$ app --user guest # where would "guest" end up?

Nowhere. When using named nested structures you should prepend parameter with struct's name via dot.

[alexflint]

After considering this some more I think this feature would add too much complexity for how widely it would end up being used. Feel free to re-open this issue if you would like to discuss further.