Best practices to add more than one bound to type parameters

[frankwswang]

@nsajko

Taking a step back, it seems like there’s another way to accomplish your goal, by using UnionAll to add a second supertype constraint:

struct myTImpl{T, N, V<:NTuple{N, T}}
    a::V
end

const TwoOrThreeTuple{T} = Union{NTuple{2, T}, NTuple{3, T}}

const myT = myTImpl{T, N, V} where {T, N, V<:TwoOrThreeTuple{T}}

function myT(a::V) where {T, N, V<:NTuple{N, T}}
    myT{T, N, V}(a)
end

This is probably the best solution so far. Thanks!

I must confess, for my own taste, I don’t really like to make myT a type alias on top of another struct type myTImpl. I intended myT to be a public composite type with a docstring explaining its fields and functionalities. With this solution, I’ll have to introduce myTImpl but still tell the users, “This is not a fully public API, and you should always stick to methods named myT” .

But it’ll do the job.