unpack columns of a ComponentMatrix

[bgctw]

Is your feature request related to a problem? Please describe.

I use ComponentArrays to pass driver data using a DataLoader to a cost function of a process based model optimization, where I extract several sub-matrices defined by named column ranges. Currently, I repeat lines for each submatrix - variable pair.

var1 = ca[:,Val(:key1)]
var2 = ca[:,Val(:key2)]
...

Describe the solution you’d like

Hence, I would like a macro similar to @static_unpack that extracts columns from a ComponentMatrix.

    xs = ComponentMatrix(collect(reshape(1:(2*5),2,5)), (Shaped1DAxis((2,)), Axis(a=1, b=2:4, c=5:5)))
    @static_unpack_col a, b, c = xs # known size
    @test a isa SVector{2, Int64}
    @test a == getdata(xs)[:, 1]

Or for larger Arrays a similar macro that provides views rather than creating StaticArrays.

Describe alternatives you’ve considered

I tried mapping across keys, but that introduces dynamic dispatch and/or type instability.
This is because, the Val(keyvar) is not a literal any more.
Omitting the Val inside the map, introduces dynamic dispatch and unstable return value.

Additional context

I provide an implementation by adapting the @static_unpack macro and an example in a test