C++核心准则C.45:使用类内初始化器初始化数据成员

C.45: Don't define a default constructor that  only initializes data members; use in-class member initializers instead

C.45:不要只初始化数据成员的默认构造函数；使用类内成员初始化器

Reason（原因）

Using in-class member initializers lets the compiler generate the function for you. The compiler-generated function can be more efficient.

使用类内初始化器可以让编译器为你生成一个函数。编译器生成的函数效率更高。

Example, bad（反面示例）

class X1 { // BAD: doesn't use member initializers
    string s;
    int i;
public:
    X1() :s{"default"}, i{1} { }
    // ...
};      

Example（示例）

class X2 {
    string s = "default";
    int i = 1;
public:
    // use compiler-generated default constructor
    // ...
};      

Enforcement(实施建议)

(Simple) A default constructor should do more than just initialize member variables with constants.

(简单)默认构造函数应该比使用常量初始化数据成员做的更多。

译者注：差不多就是杀鸡焉用牛刀的意思。

原文链接

​​https://github.com/isocpp/CppCoreGuidelines/blob/master/CppCoreGuidelines.md#c45-dont-define-a-default-constructor-that-only-initializes-data-members-use-in-class-member-initializers-instead​​