What's the usage of AsDomain? Seems like DomainRef suffices

[dlfivefifty]

DomainSetsCore.jl/src/DomainSetsCore.jl

Line 82 in 4bd09eb

abstract type AsDomain end

[daanhb]

I had modelled this after Ref in julia. Ref(5) is also not a concrete type and returns something else:

julia> Ref(5)
Base.RefValue{Int64}(5)

My thinking here was that some objects need not be modified when passed as a domain, for example AsDomain(d::Domain) = d. But since DomainRef is a concrete type, one would expect it to return an instance of DomainRef.

[dlfivefifty]

But a Domain is not a subtype of AsDomain so AsDomain(d::Domain) = d is bad style (type constructors should always return an instance of that type)

[daanhb]

That's true. I guess AsDomain could just be a function, instead of an abstract type, but then we have more names in total since the user writes foo(AsDomain(d)) and the developer writes foo(d::DomainRef) = .... We could simply use DomainRef, but in that case regular domains would have to be wrapped as well. If that's not too bad, it would admittedly be simpler.

I originally thought that AsDomain(d) might also return something else that acts like the domain which d is supposed to represent, but thinking about it now that conflates things. There already is a mechanism to convert to a domain.

Only thing left on my mind is why Ref is not a concrete type.

[daanhb]

I've removed AsDomain and just use DomainRef now. It is simpler.