Merge pull request #1272 from ven-k/discrete_connect_type

Add `connection_type` to `DiscreteSystem`

Author: YingboMa

src/systems/discrete_system/discrete_system.jl

@@ -54,13 +54,17 @@ struct DiscreteSystem <: AbstractTimeDependentSystem
     in `DiscreteSystem`.
     """
     default_p::Dict
-    function DiscreteSystem(discreteEqs, iv, dvs, ps, var_to_name, ctrls, observed, name, systems, default_u0, default_p; checks::Bool = true)
+    """
+    type: type of the system
+    """
+    connection_type::Any
+    function DiscreteSystem(discreteEqs, iv, dvs, ps, var_to_name, ctrls, observed, name, systems, default_u0, default_p, connection_type; checks::Bool = true)
         if checks
             check_variables(dvs, iv)
             check_parameters(ps, iv)
             all_dimensionless([dvs;ps;iv;ctrls]) ||check_units(discreteEqs)
         end
-        new(discreteEqs, iv, dvs, ps, var_to_name, ctrls, observed, name, systems, default_u0, default_p)
+        new(discreteEqs, iv, dvs, ps, var_to_name, ctrls, observed, name, systems, default_u0, default_p, connection_type)
     end
 end
 
@@ -78,6 +82,7 @@ function DiscreteSystem(
                    default_u0=Dict(),
                    default_p=Dict(),
                    defaults=_merge(Dict(default_u0), Dict(default_p)),
+                   connection_type=nothing,
                    kwargs...,
                   )
     name === nothing && throw(ArgumentError("The `name` keyword must be provided. Please consider using the `@named` macro"))
@@ -101,7 +106,7 @@ function DiscreteSystem(
     if length(unique(sysnames)) != length(sysnames)
         throw(ArgumentError("System names must be unique."))
     end
-    DiscreteSystem(eqs, iv′, dvs′, ps′, var_to_name, ctrl′, observed, name, systems, default_u0, default_p, kwargs...)
+    DiscreteSystem(eqs, iv′, dvs′, ps′, var_to_name, ctrl′, observed, name, systems, default_u0, default_p, connection_type, kwargs...)
 end
 
 """

test/discretesystem.jl

@@ -90,3 +90,13 @@ linearized_eqs = [
     y(t - 2.0) ~ y(t)
 ]
 @test all(eqs2 .== linearized_eqs)
+
+# Test connection_type
+@connector function DiscreteComponent(;name)
+    @variables v(t) i(t)
+    DiscreteSystem(Equation[], t, [v, i], [], name=name, defaults=Dict(v=>1.0, i=>1.0))
+end
+
+@named d1 = DiscreteComponent()
+
+@test ModelingToolkit.get_connection_type(d1) == DiscreteComponent