Suggest vcat and hcat derive from cat

[ablaom]

I've just implemented an new AbstractArray type and after overloading Base.cat for my new type, discovered that vcat also needed to be overloaded. Is there a reason vcat(A...) does not fall back to cat(A..., dims=1)?

[strickek]

#31183

[vtjnash]

It is somewhat unclear how to overload cat properly (#2326) but I believe this should generally now be true:

   1 # The specializations for 1 and 2 inputs are important
   2 vcat(A::AbstractArray) = cat(A; dims=Val(1))
   3 vcat(A::AbstractArray, B::AbstractArray) = cat(A, B; dims=Val(1))
   4 vcat(A::AbstractArray...) = cat(A...; dims=Val(1))
   5 vcat(A::Union{AbstractArray,Number}...) = cat(A...; dims=Val(1))
   6 hcat(A::AbstractArray) = cat(A; dims=Val(2))
   7 hcat(A::AbstractArray, B::AbstractArray) = cat(A, B; dims=Val(2))
   8 hcat(A::AbstractArray...) = cat(A...; dims=Val(2))
   9 hcat(A::Union{AbstractArray,Number}...) = cat(A...; dims=Val(2))

[ablaom]

Thanks @vtjnash. But to be clear, are these fallbacks that have been added since I opened the issue, or recommendations for explicit overloadings?

[vtjnash]

It is generally new now