Question about strange constructors in class
Hi there!
Have a look at the following code in a class:
The parts in bold have confused me. I see a constructor which takes a HINSTANCE and a destructor that can be over-ridden. But what are the other two lines in between those?Code:class D3DApp { protected: D3DApp(HINSTANCE hInstance); D3DApp(const D3DApp& rhs) = delete; D3DApp& operator=(const D3DApp& rhs) = delete; virtual ~D3DApp(); ....omitted
I really haven't got a clue! Thanks
They are respectively the copy constructor and assignment operator.
14.14 — Introduction to the copy constructor – Learn C++
22.3 — Move constructors and move assignment – Learn C++
21.12 — Overloading the assignment operator – Learn C++
The = delete means you're forbidding the use of these methods.
11.4 — Deleting functions – Learn C++
It's basically to prevent you from (accidentally) creating another copy of your app, using things like
Code:D3DApp a, b; a = b; // nope! D3DApp c(a); // nope!
If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
If at first you don't succeed, try writing your phone number on the exam paper.
Brilliant! Thanks very much Salem
I had a good read of that stuff, and also recently came across it on the NetAcad course I'm doing. So no use of copy constructors allowed through either the typical a = b style nor the function a(b) style. Thanks again
Reply With Quote