Merge pull request #783 from SciML/add_reaction_system_metadata

Add reaction system metadata

Author: TorkelE

src/reactionsystem.jl

@@ -508,14 +508,18 @@ struct ReactionSystem{V <: NetworkProperties} <:
     """
     discrete_events::Vector{MT.SymbolicDiscreteCallback}
     """
+    Metadata for the system, to be used by downstream packages. 
+    """
+    metadata::Any
+    """
     complete: if a model `sys` is complete, then `sys.x` no longer performs namespacing.
     """
     complete::Bool
 
     # inner constructor is considered private and may change between non-breaking releases.
     function ReactionSystem(eqs, rxs, iv, sivs, states, spcs, ps, var_to_name, observed,
                             name, systems, defaults, connection_type, nps, cls, cevs, devs,
-                            complete::Bool = false; checks::Bool = true)
+                            metadata = nothing, complete::Bool = false; checks::Bool = true)
 
         # unit checks are for ODEs and Reactions only currently
         nonrx_eqs = Equation[eq for eq in eqs if eq isa Equation]
@@ -534,7 +538,7 @@ struct ReactionSystem{V <: NetworkProperties} <:
 
         rs = new{typeof(nps)}(eqs, rxs, iv, sivs, states, spcs, ps, var_to_name, observed,
                               name, systems, defaults, connection_type, nps, cls, cevs,
-                              devs, complete)
+                              devs, metadata, complete)
         checks && validate(rs)
         rs
     end

test/reactionsystem_structure/reactionsystem.jl

@@ -763,3 +763,9 @@ let
     @test !isspecies(Y)
     @test isspecies(Catalyst.tospecies(Y))
 end
+
+# Tests metadata.
+let
+    @test isnothing(ModelingToolkit.get_metadata(rs))
+end
+