Has the new C++11 member initialization feature at declaration made initialization lists obsolete?

Question

With C++11, we now have the ability to initialize class members in a header declaration:

class aClass
{
    private:
        int mInt{100};
    public:
              


        

Answer 1

The way I look at it, in-class initialization is an ehancement of mem-initializer-lists. In C++03, members not listed in a mem-initializer-list were always default initialised. This means the default constructor for classes, and no initialization for primitive types.

In-class initialization simply allows you to specify your own defaults. There are two ways to look at it.

One: if most/all constructors of your class want to provide the same initial value for a member, use an in-class initializer for that member. For other members, use mem-initializer-lists. You'll of course have to use those whenever the initial value depends on constructor arguments.

The other one: provide an in-class initializer for all members, exactly how the default constructor of your class would initialise them. Then, mem-initializer-lists in non-default constructors get the semantics of "how it differs from a default-constructed object."