Well I think my lack of knowledge on OOP is quite deep. I was just experimenting with [this example](https://play.nim-lang.org/#ix=4f8I), which fails. You cannot convert objects like that. type Person = object of RootObj name: string Student = object of Person var a:Person var b:Student b.name = "joe" a = b Run
The [following works](https://play.nim-lang.org/#ix=4f8J): type Person = ref object of RootObj name: string Student = ref object of Person var a = new Person var b = new Student b.name = "joe" a = b b.name = "peter" assert b.name == "peter" assert a.name == "peter" assert (a of Person) assert (b of Student) Run The first issue that I have above, is trying to mimic this behaviour in C++: // Geom_CartesianPoint inherits from Geom_Point Handle(Geom_Point) aPnt1; Handle(Geom_CartesianPoint) aPnt2; aPnt2 = new Geom_CartesianPoint(); aPnt1 = aPnt2; // OK, standard assignment Run In my bindings, `Geom_CartesianPoint` inherits from `Geom_Point`. But their respective handles are unreleated. In Nim: import occt var aPnt1: Handle[Geom_Point] var aPnt2: Handle[Geom_CartesianPoint] aPnt2 = newHandle( cnew newGeomCartesianPoint(1.0,2.0,3.0) ) #aPnt1 = aPnt2 # This fails Run fails. If I replace the last line with: aPnt1 = cast[Handle[Geom_Point]](addr aPnt2) # This fails as well Run it also fails: /home/jose/.cache/nim/tmp01_d/@mtmp01.nim.cpp: In function 'void NimMainModule()': /home/jose/.cache/nim/tmp01_d/@mtmp01.nim.cpp:117:92: error: use of deleted function 'NimMainModule()::<unnamed union>::<constructor>()' 117 | union { TY__34Wf6HfOat7G9bBA2jRAzyA* source; TY__7y8d4b9bdzRBHHJhUtf9af9ag dest; } LOC1; | ^~~~ /home/jose/.cache/nim/tmp01_d/@mtmp01.nim.cpp:117:15: note: 'NimMainModule()::<unnamed union>::<constructor>()' is implicitly deleted because the default definition would be ill-formed: 117 | union { TY__34Wf6HfOat7G9bBA2jRAzyA* source; TY__7y8d4b9bdzRBHHJhUtf9af9ag dest; } LOC1; | ^ /home/jose/.cache/nim/tmp01_d/@mtmp01.nim.cpp:117:84: error: union member 'NimMainModule()::<unnamed union>::dest' with non-trivial 'opencascade::handle<T>::handle() [with T = Geom_Point]' 117 | union { TY__34Wf6HfOat7G9bBA2jRAzyA* source; TY__7y8d4b9bdzRBHHJhUtf9af9ag dest; } LOC1; | ^~~~ /home/jose/.cache/nim/tmp01_d/@mtmp01.nim.cpp:117:92: error: use of deleted function 'NimMainModule()::<unnamed union>::~<constructor>()' 117 | union { TY__34Wf6HfOat7G9bBA2jRAzyA* source; TY__7y8d4b9bdzRBHHJhUtf9af9ag dest; } LOC1; | ^~~~ /home/jose/.cache/nim/tmp01_d/@mtmp01.nim.cpp:117:15: note: 'NimMainModule()::<unnamed union>::~<constructor>()' is implicitly deleted because the default definition would be ill-formed: 117 | union { TY__34Wf6HfOat7G9bBA2jRAzyA* source; TY__7y8d4b9bdzRBHHJhUtf9af9ag dest; } LOC1; | ^ compilation terminated due to -fmax-errors=3. Error: execution of an external compiler program 'g++ -c -std=gnu++14 -funsigned-char -w -fmax-errors=3 -fpermissive -I/usr/include/opencascade/ -I/home/jose/.choosenim/toolchains/nim-1.6.6/lib -I/home/jose/src/nimlang/occt.nim/examples -o /home/jose/.cache/nim/tmp01_d/@mtmp01.nim.cpp.o /home/jose/.cache/nim/tmp01_d/@mtmp01.nim.cpp' failed with exit code: 1 Run How can I convert the references from one type to the other?
