Overload "equivalent" units methods to return info if required

[kerimoyle]

Currently we only return true/false from the Units::equivalent family of methods. I think it would be really useful to overload these to return the error message via the argument list so that people can import units and test them for equivalence without having to first create a model, assign connected variables etc etc just in order to get the mismatch information message. Thoughts?

[agarny]

I guess it could be useful to some, so sure.

[hsorby]

I think it would be more in keeping with the way things are working to have a tool that reported on the equivalence of two units, without recourse to using a model.

[agarny]

What do you mean by tool?

[kerimoyle]

Here's what I'm imagining:

bool Units::equivalent(const UnitsPtr &units1, const UnitsPtr &units2) {
// current function
}

bool Units::equivalent(const UnitsPtr &units1, const UnitsPtr &units2, std::string &hints) {
// current functionality but also returns the hints string (as from the validator) so the user can 
// access it without needing the model and validator ... 
}

[hsorby]

A class like the Validator that will perform some function.

[kerimoyle]

I guess this is related to our phone conversation @hsorby ? A more generic Checker/Debugger/Helper/Validator class that would test things as needed, with strict validation against the specification as a subset of its functionality. Have you dreamt up a name for it yet, or are you happy to leave it as Validator?

[kerimoyle]

Hmm ... would the current Units::equivalent(...) function move to be Validator::unitsAreEquivalent() ? or would we rather keep two very similar functions in two different classes?

[hsorby]

I'm definitely not happy to leave it as Validator for me that is the name of the tool that validates against the CellML 2.0 specification. Other tools need their own names.

[hsorby]

No I don't have a good name for such a tool.