C++核心准则C.140:不要为虚函数和它的覆盖函数设定不同的默认参数

C.140: Do not provide different default arguments for a virtual function and an overrider

C.140:不要为虚函数和它的覆盖函数设定不同的默认参数

Reason(原因)

That can cause confusion: An overrider does not inherit default arguments.

这可能会引起混乱：覆盖函数不会继承默认参数。

Example, bad（反面示例）

class Base {
public:
    virtual int multiply(int value, int factor = 2) = 0;
    virtual ~Base() = default;
};

class Derived : public Base {
public:
    int multiply(int value, int factor = 10) override;
};

Derived d;
Base& b = d;

b.multiply(10);  // these two calls will call the same function but
d.multiply(10);  // with different arguments and so different results

Enforcement（实施建议）

Flag default arguments on virtual functions if they differ between base and derived declarations.

如果基类和派生的虚函数和覆盖函数的默认参数不同，进行提示。

原文链接

https://github.com/isocpp/CppCoreGuidelines/blob/master/CppCoreGuidelines.md#c140-do-not-provide-different-default-arguments-for-a-virtual-function-and-an-overrider

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