Replace SystemUnitsSettings with a plain Float64 units anchor

docs/src/docs_best_practices/how-to/troubleshoot.md

@@ -82,7 +82,7 @@ Pkg.add(["PowerSystems"]);
      2. Run the formatter once to format the rest of the file
      3. Add the text back in
      4. Add the `ignore` keyword argument with the file name to
-        [`JuliaFormatter.format`](@extref `JuliaFormatter.format-Tuple{Any}`) in `scripts/formatter/formatter_code.jl`
+        [`JuliaFormatter.format`](@extref) in `scripts/formatter/formatter_code.jl`
         to skip the file in the future:
 
 ```julia

src/internal.jl

@@ -1,8 +1,6 @@
 
 import UUIDs
 
-abstract type UnitsData end
-
 @scoped_enum(UnitSystem, SYSTEM_BASE = 0, DEVICE_BASE = 1, NATURAL_UNITS = 2,)
 
 @doc """
@@ -14,14 +12,6 @@ Unit system for component data values.
 - `NATURAL_UNITS`: Values in natural units (e.g., MW, MVAR)
 """ UnitSystem
 
-@kwdef mutable struct SystemUnitsSettings <: UnitsData
-    const base_value::Float64
-    unit_system::UnitSystem
-end
-
-serialize(val::SystemUnitsSettings) = serialize_struct(val)
-deserialize(T::Type{<:SystemUnitsSettings}, val::Dict) = deserialize_struct(T, val)
-
 @kwdef struct SharedSystemReferences <: InfrastructureSystemsType
     supplemental_attribute_manager::Union{Nothing, AbstractSupplementalAttributeManager} =
         nothing
@@ -34,7 +24,7 @@ Internal storage common to InfrastructureSystems types.
 mutable struct InfrastructureSystemsInternal <: InfrastructureSystemsType
     uuid::Base.UUID
     shared_system_references::Union{Nothing, SharedSystemReferences}
-    units_info::Union{Nothing, SystemUnitsSettings}
+    base_value::Union{Nothing, Float64}
     ext::Union{Nothing, Dict{String, Any}}
 end
 
@@ -44,10 +34,10 @@ Creates InfrastructureSystemsInternal with a new UUID.
 InfrastructureSystemsInternal(;
     uuid = make_uuid(),
     shared_system_references = nothing,
-    units_info = nothing,
+    base_value = nothing,
     ext = nothing,
 ) =
-    InfrastructureSystemsInternal(uuid, shared_system_references, units_info, ext)
+    InfrastructureSystemsInternal(uuid, shared_system_references, base_value, ext)
 
 """
 Creates InfrastructureSystemsInternal with an existing UUID.
@@ -85,8 +75,16 @@ function set_shared_system_references!(
     return
 end
 
-get_units_info(internal::InfrastructureSystemsInternal) = internal.units_info
-set_units_info!(internal::InfrastructureSystemsInternal, val) = internal.units_info = val
+get_base_value(internal::InfrastructureSystemsInternal) = internal.base_value
+set_base_value!(internal::InfrastructureSystemsInternal, val) = internal.base_value = val
+
+"""
+Generic accessor for the base-value units anchor: works for anything implementing
+`get_internal`. Types that store their own anchor directly (rather than through an
+`InfrastructureSystemsInternal`) should add a concrete method instead.
+"""
+get_base_value(x::InfrastructureSystemsType) = get_base_value(get_internal(x))
+set_base_value!(x::InfrastructureSystemsType, val) = set_base_value!(get_internal(x), val)
 
 """
 Gets the UUID for any InfrastructureSystemsType.
@@ -108,9 +106,9 @@ function serialize(internal::InfrastructureSystemsInternal)
 
     for field in fieldnames(InfrastructureSystemsInternal)
         val = getproperty(internal, field)
-        # reset the units data since this is a struct related to the system the components is
-        # added which is resolved later in the de-serialization.
-        if val isa UnitsData
+        # base_value is resolved against the system the component is added to, later, at
+        # deserialization time - never serialize the live value.
+        if field == :base_value
             val = nothing
         elseif field == :shared_system_references
             continue

src/time_series_metadata_store.jl

@@ -157,8 +157,8 @@ function _load_metadata_into_memory_legacy!(store::TimeSeriesMetadataStore)
         if !isnothing(internal.ext) && !isempty(internal.ext)
             @warn "ext is no longer supported on a time series metadata instance and will be dropped: $(internal.ext)"
         end
-        if !isnothing(internal.units_info)
-            @warn "units_info is no longer supported on a time series metadata instance and will be dropped: $(internal.units_info)"
+        if !isnothing(internal.base_value)
+            @warn "base_value is no longer supported on a time series metadata instance and will be dropped: $(internal.base_value)"
         end
         uuid = get_uuid(metadata)
         if haskey(store.metadata_uuids, uuid)
@@ -492,9 +492,9 @@ function add_metadata!(
     if !isnothing(internal.ext) && !isempty(internal.ext)
         error("ext cannot be set on a time series metadata instance: $(internal.ext)")
     end
-    if !isnothing(internal.units_info)
+    if !isnothing(internal.base_value)
         error(
-            "units_info cannot be set on a time series metadata instance: $(internal.units_info)",
+            "base_value cannot be set on a time series metadata instance: $(internal.base_value)",
         )
     end
     vals = _create_row(

src/utils/print.jl

@@ -91,14 +91,6 @@ function Base.show(io::IO, ::MIME"text/html", data::SystemData)
     show_supplemental_attributes_data(io, data; backend = :html, stand_alone = false)
 end
 
-function Base.show(io::IO, ::MIME"text/plain", system_units::SystemUnitsSettings)
-    print(io, summary(system_units), ":")
-    for name in fieldnames(typeof(system_units))
-        val = getproperty(system_units, name)
-        print(io, "\n      ", name, ": ", val)
-    end
-end
-
 function Base.show(io::IO, ::MIME"text/plain", ist::TimeSeriesOwners)
     print(io, summary(ist), ":")
     for name in fieldnames(typeof(ist))

test/test_units.jl

@@ -29,9 +29,25 @@ end
     end
 end
 
-@testset "SystemUnitsSettings base_value is immutable" begin
-    settings = IS.SystemUnitsSettings(100.0, IS.UnitSystem.SYSTEM_BASE)
-    @test_throws ErrorException settings.base_value = 50.0
-    settings.unit_system = IS.UnitSystem.NATURAL_UNITS
-    @test settings.unit_system == IS.UnitSystem.NATURAL_UNITS
+@testset "InfrastructureSystemsInternal units-anchor accessors" begin
+    internal = IS.InfrastructureSystemsInternal()
+    @test IS.get_base_value(internal) === nothing
+    IS.set_base_value!(internal, 100.0)
+    @test IS.get_base_value(internal) === 100.0
+    IS.set_base_value!(internal, nothing)
+    @test IS.get_base_value(internal) === nothing
+end
+
+struct MockUnitsAnchorHolder <: IS.InfrastructureSystemsType
+    internal::IS.InfrastructureSystemsInternal
+end
+IS.get_internal(x::MockUnitsAnchorHolder) = x.internal
+
+@testset "get_base_value/set_base_value! generic forwarding via get_internal" begin
+    mock = MockUnitsAnchorHolder(IS.InfrastructureSystemsInternal())
+    @test IS.get_base_value(mock) === nothing
+    IS.set_base_value!(mock, 100.0)
+    @test IS.get_base_value(mock) === 100.0
+    IS.set_base_value!(mock, nothing)
+    @test IS.get_base_value(mock) === nothing
 end