Dynamic creation of Singleton

[d_stranz]

sadly it seems there is no way to invoke a static method without a previous instance of the class.

That's not true at all. Static methods do not require any class instance to invoke. You use the syntax:

result = MyClass::myStaticMethod();

result = MyClass::myStaticMethod();

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A common way to implement a Singleton class is to use a static class method along with a static pointer:

// MyClass.h
class MyClass
{
  private:
    MyClass *  pInstance;
 
    MyClass();
    ~MyClass();
 
  public:
    static MyClass * instance()
    {
       if ( !pInstance )
         pInstance = new MyClass();
 
       return pInstance;
     }
 
};
 
// MyClass.cpp;
MyClass::pInstance * instance = 0;
 
MyClass * pSingleton = MyClass::instance();

// MyClass.h
class MyClass
{
  private:
    MyClass *  pInstance;

    MyClass();
    ~MyClass();

  public:
    static MyClass * instance()
    {
       if ( !pInstance )
         pInstance = new MyClass();

       return pInstance;
     }
 
};

// MyClass.cpp;
MyClass::pInstance * instance = 0;

MyClass * pSingleton = MyClass::instance();

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This leaves a dangling pInstance memory leak when the program exits, but you can implement code to clean that up if necessary.

[remizero]

Hi d_stranz.

I fully understand what you say, I know how to call a static method.

I am referring to the invocation of a static method without instance through QMetaObject :: InvokeMethod (), work with this class makes it impossible to invoke a static method without instance: s.

But thanks for your good intentions