resources

Author: PGimenez

src/Resources.jl

@@ -0,0 +1,54 @@
+module Resources
+using ..Signals
+export Resource
+
+struct Resource
+    id::Symbol
+    value::Signal
+    loader::Function
+    isloading::Signal{Bool}
+    sources::Vector{Signal}
+    error::Signal
+end
+
+function Resource(loader::Function, sources::Vector{<:Signal}, id = :none)
+    value = Signal(nothing)
+    isloading = Signal(false)
+    error = Signal(nothing)
+
+    resource = Resource(id, value, loader, isloading, sources, error)
+
+    # Create computed signal to track dependencies
+    trigger = computed(() -> begin
+        # Read all source signals
+       map(s -> s(), sources)
+       nothing
+    end)
+
+    effect_fn = () -> begin
+        isloading() && return
+        isloading(true)
+        try
+            result = loader()
+            value(result)
+            error(nothing)
+        catch e
+            error(e)
+            value(nothing)
+        finally
+            isloading(false)
+        end
+    end
+    push!(trigger.effects, effect_fn)
+
+    resource
+end
+
+function (resource::Resource)()
+    resource.value()
+end
+
+loading(resource::Resource) = resource.isloading()
+value(resource::Resource) = resource.value()
+
+end

src/Signals.jl

@@ -23,6 +23,7 @@ end
 COMPUTED_DEPS::Set{Signal} = Set{Signal}()
 
 Signal(x) = Signal(x, nothing, true, nothing, Set{Signal}(), Set{Function}())
+Signal(::Nothing) = Signal{Union{Any,Nothing}}(nothing, nothing, true, nothing, Set{Signal}(), Set{Function}())
 Signal(x, id::Union{Symbol,Nothing}) = Signal(x, id, true, nothing, Set{Signal}(), Set{Function}())
 Signal(f::Function, id::Union{Symbol,Nothing}=nothing) = Signal(f(), id, true, f, Set{Signal}(), Set{Function}())
 

src/StateSignals.jl

@@ -1,8 +1,12 @@
 module StateSignals
 include("Signals.jl")
+include("Resources.jl")
 
 using .Signals
+using .Resources
 export Signal, computed, effect, invalidate, pull!
 export CONTEXT_SIGNALS
 
+export Resource
+
 end

test/test-resources.jl

@@ -0,0 +1,80 @@
+using Test
+using StateSignals
+
+@testset "Basic Resource Operations" begin
+    # Test resource creation
+    s = Signal(0)
+    r = Resource([s]) do
+        s() * 2
+    end
+
+    @test r() === nothing  # Initial value should be nothing
+    @test r.isloading() == false  # Should not be loading initially
+
+    # Test resource loading
+    s(5)
+    sleep(0.1)
+    @test r() == 10  # Should compute s() * 2
+    @test r.isloading() == false  # Should be done loading
+end
+
+@testset "Resource Loading State" begin
+    s = Signal(0)
+    loading_states = []
+
+    r = Resource([s]) do
+        # Track loading state changes
+        push!(loading_states, r.isloading())
+        sleep(0.1)  # Simulate async work
+        s() * 2
+    end
+
+    s(5)
+    sleep(0.2)  # Wait for async operation
+
+    @test loading_states[1] == true  # Should be loading during computation
+    @test r.isloading() == false  # Should be done loading after computation
+    @test r() == 10  # Should have correct final value
+end
+
+@testset "Multiple Dependencies" begin
+    a = Signal(2)
+    b = Signal(3)
+
+    r = Resource([a, b]) do
+        a() * b()
+    end
+
+    @test r() === nothing  # Initial value
+
+    a(4)  # Should trigger resource update
+    sleep(0.1)
+    @test r() == 12  # 4 * 3
+
+    b(5)  # Should trigger another update
+    sleep(0.1)
+    @test r() == 20  # 4 * 5
+end
+
+@testset "Error Handling" begin
+    s = Signal(0)
+    r = Resource([s]) do
+        if s() < 0
+            error("Value cannot be negative")
+        end
+        s() * 2
+    end
+
+    # Initial state
+    @test r() === nothing
+    @test r.error() === nothing
+    @test r.isloading() == false
+
+    # Test error condition
+    s(-1)
+    sleep(0.1)
+    @test r() === nothing  # Value should be reset
+    @test r.error() isa ErrorException  # Should have captured the error
+    @test r.error().msg == "Value cannot be negative"
+    @test r.isloading() == false  # Should not be loading after error
+end

test/test-signals.jl

@@ -44,6 +44,7 @@ end
     @test tracked_value[] == 1  # Initial effect run
 
     s(2)  # Should trigger effect
+    sleep(0.1)
     @test tracked_value[] == 2
 end