Private constructor and make_shared

Question

I have a singleton class with a private constructor. In the static factory method I do the following:

shared_ptr MyClass::GetInstance()
{
             


        

Answer 1

Please take VTT's comment seriously.

---

To your question:

My question is: why new can invoke a private constructor but make_shared not?

The new is actually used within a lambda in a member-function; Well, A lambda defines a local-class, and C++ standards permits a local-class within a member-function to access everything the member-function can access. And its trivial to remember that member functions can access privates..

std::make_shared has no access to the privates of MyClass. It's outside the scope of MyClass

---

Example:

class X{
    X(){};
public:
    static X* create(){ // This member-function can access private functions and ctors/dtor
        auto lm = [](){ // This lambda inherits the same access of enclosing member-function
               return new X();
        };
        return lm();
    }
};

int main(){
    auto x = X::create();    //valid;
    auto y = new X();        //invalid;
}