C.49: Prefer initialization to assignment in constructors
C.49:构造函数中应该做的是初始化而不是赋值

 

Reason（原因）

An initialization explicitly states that initialization, rather than assignment, is done and can be more elegant and efficient. Prevents "use before set" errors.

初始化明确地表明所做的是初始化而不是赋值，而且可以做得更优美，更有效率。防止“赋值之前使用”的错误。

 

Example, good（良好示例）

 

class A {   // Good
    string s1;
public:
    A(czstring p) : s1{p} { }    // GOOD: directly construct (and the C-string is explicitly named)
    // ...
};

 

 

Example, bad（反面示例）

 

class B {   // BAD
    string s1;
public:
    B(const char* p) { s1 = p; }   // BAD: default constructor followed by assignment
    // ...
};

class C {   // UGLY, aka very bad
    int* p;
public:
    C() { cout << *p; p = new int{10}; }   // accidental use before initialized
    // ...
};

 

 

Example, better still（更好的示例）

Instead of those const char*s we could use gsl::string_span or (in C++17) std::string_view as a more general way to present arguments to a function:

相对于那些const char* s，我们应该可以使用gsl::string_span或者(C++17引入的）std::string_view作为表达函数参数怒的更加普遍的方式（https:///isocpp/CppCoreGuidelines/blob/master/#Rstr-view）。

 

class D {   // Good
    string s1;
public:
    A(string_view v) : s1{v} { }    // GOOD: directly construct
    // ...
};

 


 


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