#34 Design around OptionalUnlabeledTracker is incorrect

[KOLANICH]

1. It is a singleton, so there are issues when creating multiple CmdLine objects within the same app.
2. It is used in the constructor of the positional args rather then on adding thm to a CmdLine. It means the order in which the args objecs were created matters. But what really should matter is the order in which they are specified to be parsed.

[Daniel Aarno]

See also https://sourceforge.net/p/tclap/bugs/25/ for related issues with static variables. Fixing this in a backwards compatible way may be a bit tricky (because the Arg doesn't necessarily have access to the CmdLine object when it is created), and given that it's a pretty rare use-case (multiple CmdLine objects + Unlabeled arguments) I'm not convinced it's worth it. It should be fixed for 2.0 though. However, non-breaking patches would be welcomed.

[David Okamoto]

I think this may work in 1.4:

In CmdLine.h, add a member variable (bool _optionalUnlabeled;), initialized to false in the constructor, then check in this method:

inline void CmdLine::addToArgList(Arg *a) {
    for (ArgListIterator it = _argList.begin(); it != _argList.end(); it++)
        if (*a == *(*it))
            throw(SpecificationException(
                "Argument with same flag/name already exists!", a->longID()));

    if (!a->hasLabel()) {
        if (_optionalUnlabeled)
            throw(SpecificationException(
                "You can't specify ANY Unlabeled Arg following an optional "
                "Unlabeled Arg", a->longID()));

        if (!a->isRequired()) _optionalUnlabeled = true;
    }

    a->addToList(_argList);

    if (a->isRequired()) _numRequired++;
}

and remove the check in the unlabeled objects.