OK, so this was me misreading the documentation. Just in case anyone else
will be stuck with the same issue, here were my mistakes -
a. When declaring a derived class, the base class needs to be declared
along with the derived class, using class_<Derived, base<Base>>.
b. The reason that the objects returned with smart_ptr_constructor were
defined as smart pointers, and the first version wasn't is that the
smart_ptr declaration only allows usage of smart pointers, it doesn't
automatically force their usage.
Sorry for the noise, I should've RTFM'd twice.
*One last thing that I'm not sure about - how do I define
*smart_ptr_constructor
with arguments?
using this code
struct TextRenderModel : public RenderModel {
TextRenderModel(float left, float top, float width, float height,
const std::string
&text,
int size, int xCoord, int yCoord)
: RenderModel(SkRect::MakeXYWH(left, top, width, height)),
text(text),
fontSize(size),
xCoord(xCoord),
yCoord(yCoord) {}
std::string text;
/// Size of the font;
int fontSize;
/// X offset of the drawn text.
int xCoord;
/// Y offset of the drawn text.
int yCoord;
};
EMSCRIPTEN_BINDINGS(TextRenderModelBinding) {
emscripten::class_<TextRenderModel, emscripten::base<TextRenderModel>>("
TextRenderModel")
.smart_ptr_constructor<float, float, float, float, std::string, int, int,
int>>
("TextRenderModel", &std::make_shared<TextRenderModel>);
}
prints this error:
/render/third_party/emsdk/fastcomp/emscripten/system/include/libcxx/memory:4271:5:
error: static_assert failed due to requirement
'is_constructible<TextRenderModel>::value' "Can't construct object in
make_shared"
static_assert( is_constructible<_Tp, _Args...>::value, "Can't construct
object in make_shared" );
^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/render/third_party/emsdk/fastcomp/emscripten/system/include/libcxx/memory:4656:29:
note: in instantiation of function template specialization
'std::__2::shared_ptr<wre_model::TextRenderModel>::make_shared<>' requested
here
return shared_ptr<_Tp>::make_shared(_VSTD::forward<_Args>(__args)...);
^
./src/model/TextRenderModel.hpp:41:33: note: in instantiation of function
template specialization 'std::__2::make_shared<wre_model::TextRenderModel>'
requested here
("TextRenderModel", &std::make_shared<TextRenderModel>);
^
In file included from <built-in>:1:
In file included from ././src/pch.hpp:4:
/render/third_party/emsdk/fastcomp/emscripten/system/include/libcxx/memory:2089:66:
error: no matching constructor for initialization of
'wre_model::TextRenderModel'
_LIBCPP_INLINE_VISIBILITY constexpr __compressed_pair_elem() : __value_()
{}
On Tue, 30 Jul 2019 at 16:49, Shachar Langbeheim <[email protected]> wrote:
> I see now that the same thing happens with raw pointers, and is not an
> issue of smart pointers.
>
> On Tue, 30 Jul 2019 at 15:50, שחר לנגבהיים <[email protected]> wrote:
>
>> Hi,
>> I have a couple of structs objects, inheriting from a base struct, and
>> passed using smart pointers. I've tried to bind them using embind, but when
>> I look at the object in the debugger I see that it isn't a smart pointer
>> but a raw pointer, and when I try to pass the object to another object, I
>> get an error that the wrong type of object is passed.
>>
>> c++ code:
>> struct RenderModel {};
>>
>> EMSCRIPTEN_BINDINGS(RenderModelBinding) {
>> emscripten::class_<RenderModel>("RenderModel")
>> .constructor<>()
>> .smart_ptr<std::shared_ptr<RenderModel>>("RenderModel");
>> }
>>
>> struct GroupRenderModel : RenderModel {
>> void addModel(std::shared_ptr<wre_model::RenderModel> model) {
>> models.push_back(model);
>> }
>>
>> std::vector<std::shared_ptr<wre_model::RenderModel>> models;
>> };
>>
>> EMSCRIPTEN_BINDINGS(GroupRenderModelBinding) {
>> emscripten::class_<GroupRenderModel>("GroupRenderModel")
>> .constructor<>()
>> .function("addModel", &GroupRenderModel::addModel)
>> .smart_ptr<std::shared_ptr<GroupRenderModel>>("GroupRenderModel");
>> }
>>
>> struct TextureRenderModel : public RenderModel {};
>>
>> EMSCRIPTEN_BINDINGS(TextureRenderModelBinding) {
>> emscripten::class_<TextureRenderModel>("TextureRenderModel")
>> .constructor<>()
>> .smart_ptr<std::shared_ptr<TextureRenderModel>>("TextureRenderModel");
>> }
>>
>> JS code:
>> const groupLayer = new Module.GroupRenderModel();
>> const textureLayer = new Module.TextureRenderModel();
>> groupLayer.addModel(textureLayer);
>>
>> When checking in the debugger, I see that groupLayer's pointer is:
>>
>> 1. ptrType: RegisteredPointer
>> 1. destructorFunction: null
>> 2. isConst: false
>> 3. isReference: false
>> 4. isSmartPointer: false
>> 5. name: "GroupRenderModel*"
>>
>> textureLayer's pointer is:
>>
>> 1. ptrType: RegisteredPointer
>> 1. destructorFunction: null
>> 2. isConst: false
>> 3. isReference: false
>> 4. isSmartPointer: false
>> 5. name: "TextureRenderModel*"
>>
>> And the error printed when calling setModel is:
>>
>> 1. BindingError {name: "BindingError", message: "Expected null or
>> instance of RenderModel, got an instance of TextureRenderModel", stack:
>> "BindingError: Expected null or instance of
>> RenderM…ttp://localhost:51840/client.e31bb0bc.js:68387:15"}
>> 2. message: "Expected null or instance of RenderModel, got an
>> instance of TextureRenderModel"
>> 1. name: "BindingError"
>> 2. stack: "BindingError: Expected null or instance of RenderModel,
>> got an instance of TextureRenderModel↵ at BindingError.<anonymous> (
>> http://localhost:51840/render/appWASM.js:5207:24)↵ at new
>> BindingError (eval at createNamedFunction (
>> http://localhost:51840/render/appWASM.js:1:1), <anonymous>:4:34)↵
>> at throwBindingError (
>> http://localhost:51840/render/appWASM.js:5225:13)↵ at
>> upcastPointer (http://localhost:51840/render/appWASM.js:5569:15)↵
>> at RegisteredPointer.genericPointerToWireType [as toWireType] (
>> http://localhost:51840/render/appWASM.js:5622:13)↵ at
>> GroupRenderModel$addModel [as addModel] (eval at new_ (
>> http://localhost:51840/render/appWASM.js:1:1), <anonymous>:9:26)↵
>> at CompositionCanvas.updateRenderEngine (
>> http://localhost:51840/client.e31bb0bc.js:68401:18)↵ at
>> http://localhost:51840/client.e31bb0bc.js:68387:15";
>> 3. __proto__: Error
>>
>>
>> Using smart_ptr_constructor changes the value in isSmartPointer, but the
>> same binding error is returned.
>>
>> struct RenderModel {};
>>
>> EMSCRIPTEN_BINDINGS(RenderModelBinding) {
>> emscripten::class_<RenderModel>("RenderModel")
>> .smart_ptr_constructor<std::shared_ptr<RenderModel>>("RenderModel",
>> &std::make_shared<RenderModel>);
>> }
>>
>> struct GroupRenderModel : public RenderModel {
>> void addModel(std::shared_ptr<wre_model::RenderModel> model) {
>> models.push_back(model);
>> }
>>
>> std::vector<std::shared_ptr<wre_model::RenderModel>> models;
>> };
>>
>> EMSCRIPTEN_BINDINGS(GroupRenderModelBinding) {
>> emscripten::class_<GroupRenderModel>("GroupRenderModel")
>> .function("addModel", &GroupRenderModel::addModel)
>> .smart_ptr_constructor<std::shared_ptr<GroupRenderModel>>(
>> "GroupRenderModel", &std::make_shared<GroupRenderModel>);
>> }
>>
>> struct TextureRenderModel : public RenderModel {};
>>
>> EMSCRIPTEN_BINDINGS(TextureRenderModelBinding) {
>> emscripten::class_<TextureRenderModel>("TextureRenderModel")
>> .smart_ptr_constructor<std::shared_ptr<TextureRenderModel>>(
>> "TextureRenderModel", &std::make_shared<TextureRenderModel>);
>> }
>>
>> Am I making some mistake with my binding declaration, or does embind not
>> support implicit casting?
>>
>>
>> 1.
>>
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