Why explicitly delete the constructor instead of making it private?

Question

When/why would I want to explicitly delete my constructor? Assuming the reason is to prevent its usage, why not just make it private?

class Foo
         


        

Answer 1

why explicitly delete the constructor?

Another reason:
I use delete when I want to assure that a class is called with an initializer. I consider it as a very elegant way to achieve this without runtime checks.

The C++ compiler does this check for you.

class Foo
{
   public:
       Foo() = delete;
       Foo(int bar) : m_bar(bar) {};
   private:
       int m_bar;
}

This - very simplified - code assures that there is no instantiation like this: Foo foo;