Static observables

shallow.jl

using Observables, BenchmarkTools, Test

struct StaticObservable{T, Listeners} <: Observables.AbstractObservable{T}
    listeners::Listeners
    val::Base.RefValue{T}
end

StaticObservable(obs::Observable) = StaticObservable(tuple(obs.listeners...), Ref(obs[]))
function StaticObservable(val::Ref, listeners...) 
    _notify(val, listeners)
    StaticObservable(listeners, val)
end
function StaticObservable(val, listeners...) 
    _notify(val, listeners)
    StaticObservable(listeners, Ref(val))
end

Base.getindex(obs::StaticObservable) = obs.val[]
Observables.listeners(obs::StaticObservable) = obs.listeners

_notify(val, funcs::Tuple{}) = nothing
function _notify(val, funcs::Tuple)
    f = first(funcs)
    f(val)
    _notify(val, Base.tail(funcs))
end

function Base.notify(obs::StaticObservable)
    val = obs[]
    _notify(val, obs.listeners)
    return
end

function Base.setindex!(observable::StaticObservable, val)
    observable.val[] = val
    notify(observable)
    return val
end

struct ShallowStaticObservable{T, Listeners} <: Observables.AbstractObservable{T}
    listeners::Listeners
    ShallowStaticObservable{T}(listeners::F) where {T,F} = new{T,F}(listeners)
end

function ShallowStaticObservable(val::T, listeners...) where {T} 
    _notify(val, listeners)
    ShallowStaticObservable{T}(listeners)
end

Observables.listeners(obs::ShallowStaticObservable) = obs.listeners


function Base.setindex!(observable::ShallowStaticObservable, val)
    _notify(val, observable.listeners)
    return val
end




function evolve(d = 100)
    t = 0.0
    x = rand(d)
    renew(i) = (_) -> x[i] = rand()
    ii = rand(1:d, d)
    S = [ShallowStaticObservable(x[i], renew(ii[i]) ) for i in 1:d]
    while t < 10000.0
        Δ, i = findmin(x)
        t += Δ
        @. x -= Δ
        S[i][] = x[i] # equivalent to x[ii[i]] = rand()
        x[i] = rand()
    end
    S,t
end
S, t = @time evolve();

statobs.jl

#using Pkg
using Observables
struct StaticObservable{T, Listeners} <: Observables.AbstractObservable{T}
    listeners::Listeners
    val::Base.RefValue{T}
end

StaticObservable(obs::Observable) = StaticObservable(tuple(obs.listeners...), Ref(obs[]))

Base.getindex(obs::StaticObservable) = obs.val[]
Observables.listeners(obs::StaticObservable) = obs.listeners

_notify(val, funcs::Tuple{}) = nothing
function _notify(val, funcs::Tuple)
    f = first(funcs)
    f(val)
    @show f, val
    _notify(val, Base.tail(funcs))
end

function Base.notify(obs::StaticObservable)
    val = obs[]
    _notify(val, obs.listeners)
    return
end

function Base.setindex!(observable::StaticObservable, val)
    observable.val[] = val
    notify(observable)
    return val
end

A = Observable('A')
B = map(lowercase, A)
on(x->print("\nGot $x\n"), B)
A[] = 'B';

Astatic = StaticObservable(A)

println("Should now get c:")
Astatic[] = 'C'