Allow setproperty! for PointerWrappers with special structs (#79)

* allow setproperty! for PointerWrappers with special structs

* Update pointerwrappers.jl

src/pointerwrappers.jl

@@ -70,10 +70,11 @@ end
 function Base.setproperty!(pw::PointerWrapper{T}, name::Symbol, v) where T
   i = findfirst(isequal(name), fieldnames(T))
   if isnothing(i)
-    error("type $(string(T)) has no field $name")
+    # For some `struct`s, `fieldnames` gives `data` and not the actual field names, but we can use `Base.setproperty!` for pointers,
+    # see https://github.com/trixi-framework/P4est.jl/issues/72 and https://github.com/trixi-framework/P4est.jl/issues/79
+    return Base.setproperty!(pointer(pw), name, v)
   end
-
-  unsafe_store!(reinterpret(Ptr{fieldtype(T, i)}, pointer(pw) + fieldoffset(T, i)), v)
+  return unsafe_store!(reinterpret(Ptr{fieldtype(T, i)}, pointer(pw) + fieldoffset(T, i)), v)
 end
 
 # `[]` allows one to access the actual underlying data and

test/tests_basic.jl

@@ -44,12 +44,22 @@ end
   ptr = Base.unsafe_convert(Ptr{MyStruct}, Ref(obj))
   pw = PointerWrapper(ptr)
   @test pw.value[] == 0.0
-  pw.value[] = 1.0
+  @test_nowarn pw.value[] = 1.0
   @test pw.value[] == 1.0
   @test pw.value[1] == 1.0
-  pw.value[1] = 2.0
+  @test_nowarn pw.value[1] = 2.0
   @test pw.value[1] == 2.0
   @test pw.value[] == 2.0
+  # using `setproperty!`
+  @test_nowarn pw.value = 3.0
+  @test pw.value[1] == 3.0
+  @test pw.value[] == 3.0
+  # using `setproperty!` for special `struct`s
+  # see https://github.com/trixi-framework/P4est.jl/issues/72 and https://github.com/trixi-framework/P4est.jl/issues/79
+  @test p4est_pw.global_first_position.level[] == 29
+  @test_nowarn p4est_pw.global_first_position.level = 30
+  @test p4est_pw.global_first_position.level[] == 30
+  @test_nowarn p4est_pw.global_first_position.level = 29
 
   # test if we can set the user_pointer
   p4est_pw.user_pointer = Ptr{Cvoid}(3)