ioc

Another C++ header-only library for IoC

Important notes

This implementation requires the use of interfaces (abstract classes) and latest C++ features (C++17).

Usage

Your interface must extend the ::kitsune::ioc::ServiceBase type, passing itself as the template parameter. For example:

class MyService : public ::kitsune::ioc::ServiceBase<MyService> {
public:
  virtual void foo() = 0;
};

Then your implementation must extend the ::kitsune::ioc::Service type, passing the base and the implementation types as parameters. For example:

class MyServiceImplementation : public ::kitsune::ioc::Service<MyServiceImplementation, MyService> {
public:
  void foo() {
    std::cout << "MyServiceImplementation::foo()\n";
  }
};

You may also annotate with ::kitsune::ioc::InjectionFlags::Primary if you want your service to be provided in priority. For example:

using namespace ::kitsune::ioc;
class MyImportantServiceImplementation : public Service<MyServiceImplementation, MyService, InjectionFlags::Primary> {
public:
  void foo() {
    std::cout << "MyImportantServiceImplementation::foo()\n";
  }
};

Please note that if you attempt to register two services using the same interface as primary, a ::std::logic_error will be thrown.

In order to use a service, you may simply instantiate a ::kitsune::ioc::Injectable. For example:

::kitsune::ioc::Injectable<MyService> myServiceInstance;

// You can check if the service was injected by casting to bool
if (myServiceInstance) {
  myServiceInstance->foo();
}

If you want to get a specific implementation, you can add your service as the second parameter.

::kitsune::ioc::Injectable<MyService, MyServiceImplementation> myServiceImplementationInstance;

if (myServiceImplementationInstance) {
  myServiceImplementationInstance->foo();
}

If you need to get all instances of your service, you must call the Injector directly:

auto services = ::kitsune::ioc::Injector<MyService>::getInstance().findServices();

// services is a std::list of std::weak_ptr to MyService

Compiler notes

Due to a compiler bug on G++ and CLang, you must use the KITSUNE_INJECTABLE macro.

You may use it after the declaration of your class:

class MyServiceImplementation : public ::kitsune::ioc::Service<MyServiceImplementation, MyService> {
public:
  void foo() {
    std::cout << "MyServiceImplementation::foo()\n";
  }
};

KITSUNE_INJECTABLE(MyService, MyServiceImplementation, aVariableNameExclusiveForThisInstance);

The macro has these parameters:

• The interface class name;
• The implementation class name;
• A variable name that will be added to the global scope;