CppCoreGuidelines C: Classes and class hierarchies

Class rule summary:

C.2: Use class if the class has an invariant; use struct if the data members can vary independently

C.concrete: Concrete types

NOTE:

1、Concrete types 一般 满足 rule of six，也就是含有"C.ctor: Constructors, assignments, and destructors"中总结的六种operation。

One ideal for a class is to be a regular type. That means roughly "behaves like an int." A concrete type is the simplest kind of class. A value of regular type can be copied and the result of a copy is an independent object with the same value as the original.

If a concrete type has both = and ==, a = b should result in a == b being true.

NOTE: a = b 表示将 b 赋值给 a，a == b 表示 a 和 b 的 value相等。

Concrete classes without assignment and equality can be defined, but they are (and should be) rare. The C++ built-in types are regular, and so are standard-library classes, such as string, vector, and map.

NOTE:

Concrete types are also often referred to as value types to distinguish them from types used as part of a hierarchy.

NOTE:

1、"types used as part of a hierarchy" 是指什么？应该是polymorphic class

C.ctor: Constructors, assignments, and destructors

These functions control the lifecycle of objects: creation, copy, move, and destruction.

NOTE:

1、总结的非常好

These are default operations:

11、a default constructor: X()

2、a copy constructor: X(const X&)

3、a copy assignment: operator=(const X&)

4、a move constructor: X(X&&)

5、a move assignment: operator=(X&&)

6、a destructor: ~X()

C.defop: Default Operations