MetrologyNamespace: must constructors accept strings?

[lucascolley]

An implementation could avoid accepting strings in constructors by forcing users to choose from an Enum of possible units/dimensions. Would this be reasonable? If so, do we want to avoid forcing strings to be accepted?

[nstarman]

With an Enum how would this work with a composite unit or dimension not in the Enum?

asunit("km/(s Mpc candela)")

[lucascolley]

You could require that composite units are composed via operations on their individually constructed parts?

This does seem like a bit of a reach, and if all current libraries are happy to accept strings then I don't think we need to worry about this. Just wanted to flag it as not absolutely necessary.