Add setproperties overload

Fix #773

Author: YingboMa

Project.toml

@@ -5,6 +5,7 @@ version = "5.6.1"
 
 [deps]
 ArrayInterface = "4fba245c-0d91-5ea0-9b3e-6abc04ee57a9"
+ConstructionBase = "187b0558-2788-49d3-abe0-74a17ed4e7c9"
 DataStructures = "864edb3b-99cc-5e75-8d2d-829cb0a9cfe8"
 DiffEqBase = "2b5f629d-d688-5b77-993f-72d75c75574e"
 DiffEqJump = "c894b116-72e5-5b58-be3c-e6d8d4ac2b12"
@@ -37,6 +38,7 @@ Unitful = "1986cc42-f94f-5a68-af5c-568840ba703d"
 
 [compat]
 ArrayInterface = "2.8, 3.0"
+ConstructionBase = "1"
 DataStructures = "0.17, 0.18"
 DiffEqBase = "6.54.0"
 DiffEqJump = "6.7.5"

src/ModelingToolkit.jl

@@ -6,7 +6,7 @@ using StaticArrays, LinearAlgebra, SparseArrays, LabelledArrays
 using Latexify, Unitful, ArrayInterface
 using MacroTools
 using UnPack: @unpack
-using Setfield
+using Setfield, ConstructionBase
 using DiffEqJump
 using DataStructures
 using SpecialFunctions, NaNMath

src/systems/abstractsystem.jl

@@ -143,6 +143,25 @@ for prop in [:eqs, :iv, :states, :ps, :default_p, :default_u0, :observed, :tgrad
     end
 end
 
+Setfield.get(obj, l::Setfield.PropertyLens{field}) where {field} = getfield(obj, field)
+@generated function ConstructionBase.setproperties(obj::AbstractSystem, patch::NamedTuple)
+    if issubset(fieldnames(patch), fieldnames(obj))
+        args = map(fieldnames(obj)) do fn
+            if fn in fieldnames(patch)
+                :(patch.$fn)
+            else
+                :(getfield(obj, $(Meta.quot(fn))))
+            end
+        end
+        return Expr(:block,
+            Expr(:meta, :inline),
+            Expr(:call,:(constructorof($obj)), args...)
+        )
+    else
+        error("This should never happen. Trying to set $(typeof(obj)) with $patch.")
+    end
+end
+
 function Base.getproperty(sys::AbstractSystem, name::Symbol)
     sysname = nameof(sys)
     systems = get_systems(sys)

src/systems/diffeqs/first_order_transform.jl

@@ -5,8 +5,9 @@ Takes a Nth order ODESystem and returns a new ODESystem written in first order
 form by defining new variables which represent the N-1 derivatives.
 """
 function ode_order_lowering(sys::ODESystem)
-    eqs_lowered, new_vars = ode_order_lowering(equations(sys), sys.iv, states(sys))
-    return ODESystem(eqs_lowered, sys.iv, new_vars, sys.ps)
+    iv = independent_variable(sys)
+    eqs_lowered, new_vars = ode_order_lowering(equations(sys), iv, states(sys))
+    return ODESystem(eqs_lowered, iv, new_vars, parameters(sys))
 end
 
 function ode_order_lowering(eqs, iv, states)

src/systems/diffeqs/odesystem.jl

@@ -182,9 +182,15 @@ function collect_var!(states, parameters, var, iv)
 end
 
 # NOTE: equality does not check cached Jacobian
-Base.:(==)(sys1::ODESystem, sys2::ODESystem) =
-    _eq_unordered(sys1.eqs, sys2.eqs) && isequal(sys1.iv, sys2.iv) &&
-    _eq_unordered(sys1.states, sys2.states) && _eq_unordered(sys1.ps, sys2.ps)
+function Base.:(==)(sys1::ODESystem, sys2::ODESystem)
+    iv1 = independent_variable(sys1)
+    iv2 = independent_variable(sys2)
+    isequal(iv1, iv2) &&
+    _eq_unordered(get_eqs(sys1), get_eqs(sys2)) &&
+    _eq_unordered(get_states(sys1), get_states(sys2)) &&
+    _eq_unordered(get_ps(sys1), get_ps(sys2)) &&
+    all(s1 == s2 for (s1, s2) in zip(get_systems(sys1), get_systems(sys2)))
+end
 
 function flatten(sys::ODESystem)
     systems = get_systems(sys)