vcat methods for SVector, Real

[Datseris]

Please add methods for vcat(::SVector, ::Real). Here is one way to do it:

vcat(a::SVector, b::Number) = vcat(a, SVector(b)) 

and here is another:

@generated function expand(a::SVector{D, T}, x::Real) where {D, T}
    gens = [:(a[$k]) for k=1:D]
    quote
        return SVector{$D + 1, T}($(gens...), x)
    end
end

don't know which is best, but I think something that useful (and simple!) should be supported/ exported by StaticArrays.jl

[Datseris]

all other naive approaches a user will do fail completely vcat(svector, x) returns Array, wile SVector{D+1}(svector..., a) is very inefficent.

[andyferris]

Do we have a push method?

[Datseris]

Oh my god, yes, you do... Sorry, it was some how impossible for me to imagine this, given that in my brain only push! exists, which is in-place, which can't work with SVectors...

[andyferris]

No worries, it’s a bit confusing. @c42f should we support vcat and hcat for the purpose of array literals? If so we should reopen this.

[c42f]

This is a duplicate of #602 though, so we can continue the discussion there.

I think we should allow hcat and vcat because indeed it's the obvious thing to do. Surprising users with things which should work but happen not to is not great!

The big problem is that we can't actually implement this in general: vcat doesn't really have dispatch machinery to infer the output array type. See #602 (comment). However it could be practical to cover the binary cases, and the cases where a StaticArray occurs first.

[Datseris]

Yes, agreed. Sorry that I didn't search alot, but indeed as you say, hcat(a, x) was the intuitive thing for me to do as well.