fix: check hasname before using getname

src/systems/abstractsystem.jl

@@ -191,11 +191,15 @@ function SymbolicIndexingInterface.is_variable(sys::AbstractSystem, sym)
            hasname(sym) && is_variable(sys, getname(sym))
 end
 
+function _syms_as_symbols(syms)
+    return [hasname(sym) ? getname(sym) : Symbol(sym) for sym in syms]
+end
+
 function SymbolicIndexingInterface.is_variable(sys::AbstractSystem, sym::Symbol)
-    return any(isequal(sym), getname.(variable_symbols(sys))) ||
+    vars = _syms_as_symbols(variable_symbols(sys))
+    return any(isequal(sym), vars) ||
            count('₊', string(sym)) == 1 &&
-           count(isequal(sym), Symbol.(nameof(sys), :₊, getname.(variable_symbols(sys)))) ==
-           1
+           count(isequal(sym), Symbol.(nameof(sys), :₊, vars)) == 1
 end
 
 function SymbolicIndexingInterface.variable_index(sys::AbstractSystem, sym)
@@ -210,12 +214,12 @@ function SymbolicIndexingInterface.variable_index(sys::AbstractSystem, sym)
 end
 
 function SymbolicIndexingInterface.variable_index(sys::AbstractSystem, sym::Symbol)
-    idx = findfirst(isequal(sym), getname.(variable_symbols(sys)))
+    vars = _syms_as_symbols(variable_symbols(sys))
+    idx = findfirst(isequal(sym), vars)
     if idx !== nothing
         return idx
     elseif count('₊', string(sym)) == 1
-        return findfirst(isequal(sym),
-            Symbol.(nameof(sys), :₊, getname.(variable_symbols(sys))))
+        return findfirst(isequal(sym), Symbol.(nameof(sys), :₊, vars))
     end
     return nothing
 end
@@ -236,10 +240,10 @@ function SymbolicIndexingInterface.is_parameter(sys::AbstractSystem, sym)
 end
 
 function SymbolicIndexingInterface.is_parameter(sys::AbstractSystem, sym::Symbol)
-    return any(isequal(sym), getname.(parameter_symbols(sys))) ||
+    vars = _syms_as_symbols(parameter_symbols(sys))
+    return any(isequal(sym), vars) ||
            count('₊', string(sym)) == 1 &&
-           count(isequal(sym),
-        Symbol.(nameof(sys), :₊, getname.(parameter_symbols(sys)))) == 1
+           count(isequal(sym), Symbol.(nameof(sys), :₊, vars)) == 1
 end
 
 function SymbolicIndexingInterface.parameter_index(sys::AbstractSystem, sym)
@@ -254,12 +258,12 @@ function SymbolicIndexingInterface.parameter_index(sys::AbstractSystem, sym)
 end
 
 function SymbolicIndexingInterface.parameter_index(sys::AbstractSystem, sym::Symbol)
-    idx = findfirst(isequal(sym), getname.(parameter_symbols(sys)))
+    vars = _syms_as_symbols(parameter_symbols(sys))
+    idx = findfirst(isequal(sym), vars)
     if idx !== nothing
         return idx
     elseif count('₊', string(sym)) == 1
-        return findfirst(isequal(sym),
-            Symbol.(nameof(sys), :₊, getname.(parameter_symbols(sys))))
+        return findfirst(isequal(sym), Symbol.(nameof(sys), :₊, vars))
     end
     return nothing
 end

test/symbolic_indexing_interface.jl

@@ -77,3 +77,25 @@ analytic_function = (ps, t, x) -> -ps[1] * x * (x - 1) * sin(x) * exp(-2 * ps[1]
 @test isequal(pdesys.ps, [h => 1])
 @test isequal(parameter_symbols(pdesys), [h])
 @test isequal(parameters(pdesys), [h])
+
+# Test systems with symbols that don't have a valid `getname`
+dt = 0.1
+@variables t x(t) y(t) u(t) yd(t) ud(t) r(t)
+@parameters kp
+D = Differential(t)
+# u(n + 1) := f(u(n))
+
+eqs = [yd ~ Sample(t, dt)(y)
+    ud ~ kp * (r - yd)
+    r ~ 1.0
+
+# plant (time continuous part)
+    u ~ Hold(ud)
+    D(x) ~ -x + u
+    y ~ x]
+@named sys = ODESystem(eqs)
+ss = structural_simplify(sys) # has `Hold()(ud(t))` as a parameter
+
+@test parameter_index(ss, :kp) == 1
+@test parameter_index(ss, Symbol(Hold(ud))) == 2
+@test parameter_index(ss, Sample(t, dt)(y)) == 3