Add extend

Author: YingboMa

Project.toml

@@ -16,6 +16,7 @@ Distributions = "31c24e10-a181-5473-b8eb-7969acd0382f"
 DocStringExtensions = "ffbed154-4ef7-542d-bbb7-c09d3a79fcae"
 DomainSets = "5b8099bc-c8ec-5219-889f-1d9e522a28bf"
 IfElse = "615f187c-cbe4-4ef1-ba3b-2fcf58d6d173"
+InteractiveUtils = "b77e0a4c-d291-57a0-90e8-8db25a27a240"
 JuliaFormatter = "98e50ef6-434e-11e9-1051-2b60c6c9e899"
 LabelledArrays = "2ee39098-c373-598a-b85f-a56591580800"
 Latexify = "23fbe1c1-3f47-55db-b15f-69d7ec21a316"

src/ModelingToolkit.jl

@@ -7,9 +7,10 @@ using AbstractTrees
 using DiffEqBase, SciMLBase, Reexport
 using Distributed
 using StaticArrays, LinearAlgebra, SparseArrays, LabelledArrays
+using InteractiveUtils
 using Latexify, Unitful, ArrayInterface
 using MacroTools
-using UnPack: @unpack
+@reexport using UnPack
 using Setfield, ConstructionBase
 using DiffEqJump
 using DataStructures
@@ -139,6 +140,11 @@ include("systems/alias_elimination.jl")
 include("structural_transformation/StructuralTransformations.jl")
 @reexport using .StructuralTransformations
 
+for S in subtypes(ModelingToolkit.AbstractSystem)
+    S = nameof(S)
+    @eval convert_system(::Type{<:$S}, sys::$S) = sys
+end
+
 export ODESystem, ODEFunction, ODEFunctionExpr, ODEProblemExpr, convert_system
 export DAEFunctionExpr, DAEProblemExpr
 export SDESystem, SDEFunction, SDEFunctionExpr, SDESystemExpr
@@ -184,6 +190,6 @@ export simplify, substitute
 export build_function
 export modelingtoolkitize
 export @variables, @parameters
-export @named, @nonamespace, @namespace
+export @named, @nonamespace, @namespace, extend
 
 end # module

src/bipartite_graph.jl

@@ -2,11 +2,11 @@ module BipartiteGraphs
 
 export BipartiteEdge, BipartiteGraph
 
+using Reexport
 export 𝑠vertices, 𝑑vertices, has_𝑠vertex, has_𝑑vertex, 𝑠neighbors, 𝑑neighbors,
        𝑠edges, 𝑑edges, nsrcs, ndsts, SRC, DST
 
 using DocStringExtensions
-using Reexport
 using UnPack
 using SparseArrays
 @reexport using LightGraphs

src/systems/abstractsystem.jl

@@ -793,3 +793,24 @@ end
 function connect(syss...)
     connect(promote_connect_type(map(get_connection_type, syss)...), syss...)
 end
+
+# Inheritance
+function extend(basesys::AbstractSystem, sys::AbstractSystem; name::Symbol)
+    T = SciMLBase.parameterless_type(basesys)
+    iv = independent_variable(basesys)
+    sys = convert_system(T, sys, iv)
+    eqs = union(equations(basesys), equations(sys))
+    sts = union(states(basesys), states(sys))
+    ps = union(parameters(basesys), parameters(sys))
+    obs = union(observed(basesys), observed(sys))
+    defs = merge(defaults(basesys), defaults(sys)) # prefer `sys`
+    syss = union(get_systems(basesys), get_systems(sys))
+
+    if iv === nothing
+        T(eqs, sts, ps, observed=obs, defaults=defs, name=name, systems=syss)
+    else
+        T(eqs, iv, sts, ps, observed=obs, defaults=defs, name=name, systems=syss)
+    end
+end
+
+UnPack.unpack(sys::ModelingToolkit.AbstractSystem, ::Val{p}) where p = getproperty(sys, p; namespace=false)

src/utils.jl

@@ -126,7 +126,7 @@ function collect_differentials(eqs)
         vars!(vars, eq)
         for v in vars
             isdifferential(v) || continue
-            collect_ivs_from_nested_differential!(ivs, v)  
+            collect_ivs_from_nested_differential!(ivs, v)
         end
         empty!(vars)
     end