Add @add_kwonly to PDESystem (#768)

Author: KirillZubov

src/ModelingToolkit.jl

@@ -29,7 +29,7 @@ import SymbolicUtils: Term, Add, Mul, Pow, Sym, FnType,
                       promote_symtype
 
 import SymbolicUtils.Rewriters: Chain, Postwalk, Prewalk, Fixpoint
-
+import DiffEqBase: @add_kwonly
 using LinearAlgebra: LU, BlasInt
 
 import LightGraphs: SimpleDiGraph, add_edge!

src/systems/pde/pdesystem.jl

@@ -1,7 +1,25 @@
 struct PDESystem <: ModelingToolkit.AbstractSystem
-  eq
+  eqs
   bcs
   domain
   indvars
   depvars
+  
+  @add_kwonly function PDESystem(eqs, bcs, domain, indvars, depvars)
+      new(eqs, bcs, domain, indvars, depvars)
+  end
 end
+
+Base.getproperty(x::PDESystem, sym::Symbol) = getfield(x, sym)
+
+Base.summary(prob::PDESystem) = string(nameof(typeof(prob)))
+function Base.show(io::IO, sys::PDESystem)
+  println(io,summary(sys))
+  println(io,"eqs: ", sys.eqs)
+  println(io,"bcs: ", sys.bcs)
+  println(io,"domain: ", sys.domain)
+  println(io,"depvars: ", sys.depvars)
+  println(io,"indvars: ", sys.indvars)
+  return nothing
+end
+