Feature/stringid

[whaeck]

Added a template identifier class with internal string validation: utility::Id. The underlying id type is a string.

This Id class could be implemented as an interface from which different identifiers can inherit. The problem with this approach is that identifiers based on such an interface can be interchanged using the Id base class. E.g. an identifier for a Car could be used as if it were the identifier of a Planet if the base class is used.

By associating a template to this class (to indicate which object is identified by the Id), it will not be possible to confound Id types with different template types (because they will be considered as different types). For example: utility::Id and utility::Id are thus different types and cannot be interchanged.

The Id class also calls a template function to validate the string used in the identifier. By implementing a specialisation of the validateId function for a given type T, we can reject invalid identifiers at construction.

[jlconlin]

The name of the class should be ID. It goes against the strict naming rules, but it is an abbreviation, so it should be all caps.

[jlconlin]

Overall looks pretty good. There needs to be a slight change in the name of the class, but that's not a big deal.

I'm curious what @apmccartney thinks about this class. I can't see right away an immediate need for the class, but I can also see how it could be useful. Please educate me about this.

[whaeck]

@jlconlin This class will allow us to easily create identifier objects with underlying validation. The interface for any string based identifier is actually the same for each one. Using an interface for this would be a good thing but the problem is that if you store the base class, you'll be able to compare identifiers of objects that have nothing to do with one another (hence the example of Planet and Car). By adding the template, the identifier becomes a different type for each object we wish to identify.

In addition, we can add a validateId function to make sure that an Id object is a valid object for the type it is identifying.

For example:

// forward declaration of the Reaction class
nuclearData::API::Reaction {};

// typedef the ReactionId
typedef utility::Id<nuclearData:API::Reaction> ReactionId;

// define the validateId function
template <> bool utility::validateId<nuclearData::API::Reaction>(const string& id) noexcept {

  if (id == "total") {

    return true;
  }
  return false;
}

[apmccartney]

@jlconlin doxygen has grouping specifications apparently.

[jlconlin]

What do you mean?

[apmccartney]

https://www.stack.nl/~dimitri/doxygen/manual/grouping.html

[apmccartney]

Missed name update.

[whaeck]

Nice catch!