refactor: pass the symbolic vals for kwargs of sub components instead of depending on the numerical value of it

- this change allows user to set a parameter with initial value and pass that as default value of kwargs of sub components.

Author: ven-k

src/systems/model_parsing.jl

@@ -236,7 +236,8 @@ end
 
 function parse_components!(exprs, cs, dict, body, kwargs)
     expr = Expr(:block)
-    push!(exprs, expr)
+    varexpr = Expr(:block)
+    push!(exprs, varexpr)
     comps = Vector{Symbol}[]
     for arg in body.args
         arg isa LineNumberNode && continue
@@ -247,23 +248,25 @@ function parse_components!(exprs, cs, dict, body, kwargs)
                 arg = deepcopy(arg)
                 b = deepcopy(arg.args[2])
 
-                component_args!(a, b, expr, kwargs)
+                component_args!(a, b, dict, expr, varexpr, kwargs)
 
-                push!(b.args, Expr(:kw, :name, Meta.quot(a)))
                 arg.args[2] = b
                 push!(expr.args, arg)
             end
             _ => error("`@components` only takes assignment expressions. Got $arg")
         end
     end
+
+    push!(exprs, :(@named $expr))
+
     dict[:components] = comps
 end
 
 function _rename(compname, varname)
     compname = Symbol(compname, :__, varname)
 end
 
-function component_args!(a, b, expr, kwargs)
+function component_args!(a, b, dict, expr, varexpr, kwargs)
     # Whenever `b` is a function call, skip the first arg aka the function name.
     # Whenever it is a kwargs list, include it.
     start = b.head == :call ? 2 : 1
@@ -274,15 +277,19 @@ function component_args!(a, b, expr, kwargs)
             x::Symbol || Expr(:kw, x) => begin
                 _v = _rename(a, x)
                 b.args[i] = Expr(:kw, x, _v)
+                push!(varexpr.args, :((@isdefined $x) && ($_v = $x)))
                 push!(kwargs, Expr(:kw, _v, nothing))
+                dict[:kwargs][_v] = nothing
             end
             Expr(:parameters, x...) => begin
-                component_args!(a, arg, expr, kwargs)
+                component_args!(a, arg, dict, expr, varexpr, kwargs)
             end
             Expr(:kw, x, y) => begin
                 _v = _rename(a, x)
                 b.args[i] = Expr(:kw, x, _v)
-                push!(kwargs, Expr(:kw, _v, y))
+                push!(varexpr.args, :($_v = $_v === nothing ? $y : $_v))
+                push!(kwargs, Expr(:kw, _v, nothing))
+                dict[:kwargs][_v] = nothing
             end
             _ => error("Could not parse $arg of component $a")
         end

test/model_parsing.jl

@@ -1,5 +1,6 @@
 using ModelingToolkit, Test
-using ModelingToolkit: get_gui_metadata, VariableDescription, getdefault, RegularConnector
+using ModelingToolkit: get_gui_metadata,
+    VariableDescription, getdefault, RegularConnector, get_ps
 using URIs: URI
 using Distributions
 using Unitful
@@ -120,9 +121,13 @@ end
 end
 
 @mtkmodel RC begin
+    @parameters begin
+        R_val = 10
+        C_val = 5
+    end
     @components begin
-        resistor = Resistor(; R)
-        capacitor = Capacitor(; C = 10)
+        resistor = Resistor(; R = R_val)
+        capacitor = Capacitor(; C = C_val)
         source = Voltage()
         constant = Constant(; k = 1)
         ground = Ground()
@@ -135,9 +140,10 @@ end
     end
 end
 
-@named rc = RC(; resistor.R = 20)
-@test getdefault(rc.resistor.R) == 20
-@test getdefault(rc.capacitor.C) == 10
+@named rc = RC(; R_val = 20)
+params = ModelingToolkit.get_ps(rc)
+@test isequal(getdefault(rc.resistor.R), params[1])
+@test isequal(getdefault(rc.capacitor.C), params[2])
 @test getdefault(rc.capacitor.v) == 0.0
 @test getdefault(rc.constant.k) == 1
 
@@ -210,14 +216,15 @@ end
 end
 
 @named a = A(p = 10)
-getdefault(a.b.i) == 10
-getdefault(a.b.j) == 0.1
-getdefault(a.b.k) == 1
+params = get_ps(a)
+@test isequal(getdefault(a.b.i), params[1])
+@test isequal(getdefault(a.b.j), 1 / params[1])
+@test getdefault(a.b.k) == 1
 
 @named a = A(p = 10, b.i = 20, b.j = 30, b.k = 40)
-getdefault(a.b.i) == 20
-getdefault(a.b.j) == 30
-getdefault(a.b.k) == 40
+@test getdefault(a.b.i) == 20
+@test getdefault(a.b.j) == 30
+@test getdefault(a.b.k) == 40
 
 metadata = Dict(:description => "Variable to test metadata in the Model.structure",
     :input => true, :bounds => (-1, 1), :connection_type => :Flow, :integer => true,