I think your problem is that the constructor that is bound for the
History_Tree class is one that returns raw pointers instead of smart
pointers. What you have right now is roughly equivalent to the following
C++:
int main() {
auto t = new History_Tree();
t->append_next_move(15);
return 0;
}
If you build a native executable of this and run it, you should get
something like:
terminate called after throwing an instance of 'std::bad_weak_ptr'
what(): std::bad_weak_ptr
Aborted
This is probably the cause of the exception you are seeing when running in
JavaScript. The reason this exception occurs in C++ is because
shared_from_this() may only be called on objects that have already been
stored in a std::shared_ptr:
http://en.cppreference.com/w/cpp/memory/enable_shared_from_this/shared_from_this#Notes
In this case, you want bindings that behave more like the following C++,
which first puts the object in a std::shared_ptr:
int main() {
auto t = std::make_shared<History_Tree>();
t->append_next_move(15);
return 0;
}
...in which case you probably want to bind the constructor like this:
EMSCRIPTEN_BINDINGS(History_Tree) {
emscripten::class_<History_Tree>("History_Tree")
.smart_ptr_constructor("History_TreePtr",
&std::make_shared<History_Tree>)
.function("append_next_move", &History_Tree::append_next_move)
;
}
On Monday, August 1, 2016 at 12:50:20 AM UTC-7, Jordan Bouchoucha wrote:
>
> Hi,
>
>
> Firstly, sorry for my bad English, I hope you will understand me clearly.
>
>
> I search solution for my issues this week without success... It's why i
> post here now.
> I'm working in a C++ Tree module (very basic) and i need to use it in
> Javascript.
>
>
> I show you the code resume :
>
>
> Tree.h
>
>
> #include <vector>
>> #include <memory>
>> #include <iostream>
>> #include <vector>
>> #include <string>
>> #include <emscripten/bind.h>
>>
>> class History_Tree : public std::enable_shared_from_this<History_Tree>
>> {
>> private:
>>
>> struct Move {
>> int move;
>> std::shared_ptr<History_Tree> children;
>> };
>>
>> std::weak_ptr<History_Tree> parent;
>> std::vector<Move> childrens;
>>
>> public:
>>
>> History_Tree()
>> {}
>>
>> History_Tree(std::weak_ptr<History_Tree> parent): parent(parent)
>> {}
>>
>> void append_next_move(int move);
>> std::shared_ptr<History_Tree> get_ptr();
>>
>> };
>>
>>
>
> Tree.cpp
>
>
> #include "Tree.h"
>>
>> //////////////////////////////////////////////////////////////////////////
>> void History_Tree::append_next_move(int move)
>> //////////////////////////////////////////////////////////////////////////
>> {
>> Move m;
>> m.move = move;
>> m.children = std::make_shared<History_Tree>(get_ptr());
>>
>> childrens.push_back(m);
>> }
>>
>> //////////////////////////////////////////////////////////////////////////
>> std::shared_ptr<History_Tree> History_Tree::get_ptr()
>> //////////////////////////////////////////////////////////////////////////
>> {
>> return shared_from_this();
>> }
>>
>> EMSCRIPTEN_BINDINGS(History_Tree) {
>> emscripten::class_<History_Tree>("History_Tree")
>> .constructor<>()
>> .smart_ptr<std::shared_ptr<History_Tree>>("History_TreePtr")
>> .function("append_next_move", &History_Tree::append_next_move)
>> ;
>> }
>>
>>
>
> As you can see in the bottom of .cpp, I did EMSCRIPTEN_BINDINGS for try to
> use my class in .js.
> After this i compile with this command :
>
>
> em++ --bind -o Tree.js Tree.cpp
>
>
>
> Seems to work even if i got a warning "unresolved symbol:
> throwInternalError". I call my Tree.js in a html file, and try to do this :
>
>
> var t = new Module.History_Tree();
>
>
>
>> t.append_next_move(15);
>>
>
>
> The "append_next_move()" doesn't work. I can read in my browser Javascript
> console "uncaught exception: 5271640".
>
> After doing research, I guess that it is a variable address. The bug
> appear when he read this line from Tree.cpp in "append_next_move()" :
>
> m.children = std::make_shared<History_Tree>(get_ptr());
>
> I probably misunderstand something... I don't know what is wrong exactly
> and how fix this. (In the begin, I was using WebIDL Binder but not work too
> haha...)
>
> Maybe I need to say in EMSCRIPTEN_BINDINGS that History_Tree is
> enable_shared_from_this ? I don't know...
>
> Hope you will say to me "You're an idiot, the solution is ...". That would
> be cool :D
>
>
> For testing this, you just need to :
>
> - Copy the Tree.cpp and Tree.h
> - Compile with the command em++
> - Create this .html
>
> <!doctype html>
>> <html lang="fr">
>> <head>
>> <meta charset="utf-8">
>> <title>Error test</title>
>> <script type="text/javascript" src="test.js"></script>
>> </head>
>> <body>
>>
>> <script>
>> var t = new Module.History_Tree();
>> t.append_next_move(15);
>> </script>
>>
>> </body>
>> </html>
>>
>>
> - Open it in your browser and look at console.
>
>
> Thanks for helping me.
>
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