如何用非平凡的构造函数初始化静态类成员？

Question

It is trivial in C#, but in C++ (native, Win32, Visual C++) I don't see solution. So, I have class MyClass1 with non-trivial constructor, and in MyClass2 I want to have static member of type MyClass1:

MyClass1.h:

class MyClass1 
{
   public MyClass1(type1 arg1, type2 arg2);
}

MyClass2.h:

class MyClass2
{
public:
   static MyClass1 Field1;
}

And MyClass2.cpp:

MyClass1 MyClass2::Field1(arg1, arg2);

I expect that such code will initialize MyClass2::Field and call MyClass1 constructor during this initialization. However, it looks like compiler allocates memory for Class1 only, and never calls constructor, like if I do this:

MyClass1 MyClass2::Field1 = *(MyClass1 *)malloc(sizeof(MyClass1));

Is there any "official" way in C++ to initialize static class member with nontrivial constructor?

Answer 1

You may be encountering the Static Initialization Order Fiasco . Static variables of class or namespace scope are initialized before main() is executed, but the order of initialization is dependent on link-time factors.

To solve the problem, use the Construct on First Use Idiom , which takes advantage of the fact that function-scope statics are initialized at the time the function is first called.

Answer 2

I would not expect this kind of exception that Vitaliy is getting. Static Initialization Order Fiasco requires two objects where initialization of one object invokes a method on another object.

Here we have a static initializer in MyClass2 that invokes a constructor (not a method) of another class (MyClass1). Of course, we don't need to initialize object before invoking constructor.

In summary, I don't know why Vitaliy is getting this exception. I would be interested to know the answer, but it seems that it is not due to Static Initializer Order Fiasco.