Question

I was just thinking if the new C++11 in-class member initializers could be used to initialize Singletons at compile-time, which might be a speed-up for some Manager-Classes in my applications:

class CSingleton
{
public:
    CSingleton(void) {}
    ~CSingleton(void) {}
    static const CSingleton* GetInstance(void)
    {
        return Instance;
    }

    bool Foo1(int x);
    bool Foo2(int y);
private:
    static constexpr CSingleton *Instance = new CSingleton();
}

The problem is this results in following errors:

Line of Instance declaration:    error: invalid use of incomplete type 'class test::CSingleton'
First Line of class declaration: error: forward declaration of 'class test::CSingleton'

Is there a way to initialize Singletons during compile-time with this or another approach?

[I am using GCC4.7 on MacOSX10.7 (and Ubuntu) with -std=c++0x flag set]

Answer 1

in .h file member of class:

static CSingleton s_Instance;

in .cpp file in the begining right after include

CSingleton::s_Instance = CSingleton();

This is initialization in compile time.
using new – this is initialization in runtime. Formally both of them initialization in compile time.