In C++ aggregate initialization can be done as T object = { arg1, arg2, ...} or T object{arg1, arg2, ...}. Designated initializers are supported since C++20.
Aggregate
An aggregate is one of the following types:
- array
- class, but it should follow these restrictions
- Constructors
- For C++11: Can’t have any user-declared, inherited or explicit constructors
- For C++20: Can’t have any user-declared or inherited constructors
- No private or protected non-static data members
- Base classes:
- Till C++17: no base classes
- Since C++17: no private or protected base classes. No irtual base classes
- Constructors
Element
An element of an aggregate for a class is non-static members in declaration order. Since C++17, aggregates can have public base classes. So the elements will be direct base classes in declaration order followed by non-static members in declaration order.