Make at named more intuitive

Author: YingboMa

src/systems/abstractsystem.jl

@@ -845,12 +845,21 @@ function _named(name, call, runtime = false)
         end
     end
 
+    is_sys_construction = Symbol("###__is_system_construction###")
     kws = call.args[2].args
+    for kw in kws
+        kw.args[2] = :($is_sys_construction ? $(kw.args[2]) :
+                       $default_to_parentscope($(kw.args[2])))
+    end
 
     if !any(kw -> (kw isa Symbol ? kw : kw.args[1]) == :name, kws) # don't overwrite `name` kwarg
         pushfirst!(kws, Expr(:kw, :name, runtime ? name : Meta.quot(name)))
     end
-    call
+    op = call.args[1]
+    quote
+        $is_sys_construction = ($op isa $DataType) && ($op <: $AbstractSystem)
+        $call
+    end
 end
 
 function _named_idxs(name::Symbol, idxs, call)
@@ -877,7 +886,10 @@ end
     @named y[1:10] = foo(x)
     @named y 1:10 i -> foo(x*i)  # This is not recommended
 
-Pass the LHS name to the model.
+Pass the LHS name to the model. When it's calling anything that's not an
+AbstractSystem, it wraps all keyword arguments in `default_to_parentscope` so
+that namespacing works intuitively when passing a symbolic default into a
+component.
 
 Examples:
 ```julia-repl
@@ -920,6 +932,11 @@ macro named(name::Symbol, idxs, call)
     esc(_named_idxs(name, idxs, call))
 end
 
+function default_to_parentscope(v)
+    uv = unwrap(v)
+    uv isa Symbolic && !hasmetadata(uv, SymScope) ? ParentScope(v) : v
+end
+
 function _config(expr, namespace)
     cn = Base.Fix2(_config, namespace)
     if Meta.isexpr(expr, :.)

test/components.jl

@@ -2,6 +2,7 @@ using Test
 using ModelingToolkit, OrdinaryDiffEq
 using ModelingToolkit.BipartiteGraphs
 using ModelingToolkit.StructuralTransformations
+include("../examples/rc_model.jl")
 
 function check_contract(sys)
     state = ModelingToolkit.get_tearing_state(sys)
@@ -74,7 +75,8 @@ let
     params = [param_r1 => 1.0, param_c1 => 1.0]
     tspan = (0.0, 10.0)
 
-    @test_throws Any prob=ODAEProblem(sys, u0, tspan, params)
+    prob = ODAEProblem(sys, u0, tspan, params)
+    @test solve(prob, Tsit5()).retcode == :Success
 end
 
 let
@@ -96,17 +98,16 @@ let
 end
 
 # Outer/inner connections
-function rc_component(; name)
-    R = 1
-    C = 1
+function rc_component(; name, R = 1, C = 1)
+    @parameters R=R C=C
     @named p = Pin()
     @named n = Pin()
-    @named resistor = Resistor(R = R)
-    @named capacitor = Capacitor(C = C)
+    @named resistor = Resistor(R = R) # test parent scope default of @named
+    @named capacitor = Capacitor(C = ParentScope(C))
     eqs = [connect(p, resistor.p);
            connect(resistor.n, capacitor.p);
            connect(capacitor.n, n)]
-    @named sys = ODESystem(eqs, t)
+    @named sys = ODESystem(eqs, t, [], [R, C])
     compose(sys, [p, n, resistor, capacitor]; name = name)
 end