Splitting kwargs into specific keyword arguments?

General Usage
10

I ended up using this

function splitkwargs(kwargs, args...)
    for f in args
        isa(f, Array{Symbol}) ? nothing : throw(ArgumentError("args are not arrays of symbols"))
    end
    wrongKeywordArguments = setdiff(keys(kwargs), union(args...))
    if length(wrongKeywordArguments) != 0 
        throw(UndefKeywordError(wrongKeywordArguments[1]))
    end
    out = []
    for kwarg in args
        push!(out, (;[(key, kwargs[key]) for key in intersect(keys(kwargs), kwarg)]...))
    end
    return length(out) == 1 ? out[1] : out
end

which could be used here like so:

function useAB(: kwargs...)
    #notmyfun has kwargs {calc, norm}
    funAkwargs, funBkwargs, notmyfunkwargs = splitkwargs(kwargs, [:a], [:b], [:calc, :norm])
    return funA(;funAkwargs...) + funB(;funBkwargs...) + notmyfun(;notmyfunkwargs...)

I’m not sure if there will be some problems with this approach, but oh well…