C++ via C#Egor Bogatov@EgorBo

Calling C++ from C#. For what?

• Lovely IDE + R#• Syntactic sugar• nuget

Calling C++ from C#. How?

• C++/CLI• COM• [DllImport],

[MethodImpl]• IPC, Sockets,…

Calling C++ from C#. How?

• C++/CLI• COM• [DllImport],

[MethodImpl]• IPC, Sockets,…

UrhoSharp• ~ 200 classes• ~ 5000 methods• Same FPS• +10% memory• C# for: Windows Mac OS Android iOS tvOS

Urho3D APIclass Node : public Animatable{public: Node(Context* context);

void SetName(const String& name); const String& GetName();

void SetPosition(const Vector3& position); const Vector3& GetPosition();

void AddChild(Node* node, unsigned index = M_MAX_UNSIGNED); void RemoveChild(Node* node);};

public class Node : Animatable{ public Node(Context context) { }

public string Name { get; set; } public Vector3 Position { get; set; }

void AddChild(Node node, uint index = uint.MaxValue) { } void RemoveChild(Node node) { }}

Node.cpp

C++

C#

Urho3D API

class Node : public Animatable{public:

Node(Context* context);

void SetName(const String& name);};

glue.cpp

Urho3D API

Node.cpp

C#Node node = new Node(context);node.SetName("foo");

Node* node = new Node(context_);node->SetName("foo");

Urho3D APIvoid SetName(const String& name);

extern "C"DllExport void Node_SetName (Node *target, const char * name){ target->SetName (Urho3D::String(name));}

[DllImport ("mono-urho", …)]static extern void Node_SetName (IntPtr handle, string name);

public void SetName (string name) { Node_SetName (handle, name);

Node.cppNode.h

binding.cpp

Node.cs

original API

generated

generated

Urho3D APIclass Node : public Animatable{public:

Node(Context* context); void SetName(const String& name);};

DllExport void* Node_Node (Context * context) { return new Node(context);}

DllExport void Node_SetName (Node *target, const char * name) { target->SetName (Urho3D::String(name));}

public partial class Node : Animatable{

private IntPtr handle;

[DllImport ("mono-urho")]static extern IntPtr Node_Node (IntPtr context);public Node (Context context) { handle = Node_Node (context.Handle); }

[DllImport ("mono-urho")]static extern void Node_SetName (IntPtr handle, string name);public void SetName (string name) { Node_SetName (handle, name);

Node.cppNode.h

binding.cpp

Node.cs

original API

generated

generated

Binding flow

Urho3D sources (*.cpp, *.h)

Urho.pch

Generator (Binder)

binding.cpp *.cs

UrhoSharp.dllWin: mono-urho.dllDroid: libmono-urho.soOSX: libmono-urho.dylibiOS: urho.framework

nuget package

all-urho.cpp via clang

roslyn

• clang• gcc• msvc

clang.dllNrefactory.dll

PCL, Profile7

Object lifecycleRefCounted:• AddRef • ReleaseRef• RefsCount• ~dctor

Node node = new Node(context)

1) Allocate a native object (Node* node = new Node)

scene.AddNode(node)

2) AddRef is called, callback to managed code3) Managed code receives the callback, adds hard reference to node

scene.RemoveAll();

5) Managed code receives callback from native ~dctor, removes reference. GC is now able to collect empty wrapper.

6) GC collects managed wrapper

Egor Bogatov@EgorBo

github:• UrhoSharp• CppSharp