@bind for Observables

[aplavin]

Observables.jl is a widely used package defining, well Observable(). It would be useful to bind Pluto UI elements to Observables, so that supporting libraries (such as Makie) update values efficiently.

I tried to make a macro @bindobs that works similar to @bind but defines an observable. I didn't manage to implement it properly, so would be happy to know if I missed something, or is such a thing not supported yet. What I achieved is a "two-part" macro:

macro bindobs(def::Symbol, element)
    defraw = Symbol(def, :____raw)
    quote
        elt = $element
        $(esc(def)) = Observable(get(elt))
        @bind $defraw elt
    end
end

macro bindobs_(def::Symbol)
    defraw = Symbol(def, :____raw)
    :($(esc(def))[] = $(esc(defraw)))
end

then, in one cell do @bindobs myval Slider(...) and in another cell @bindobs_ myval.

Can this be done in a single cell?