好pratice：纯虚方法的默认参数

问题描述

我创建了一个抽象基类，它有一个带有默认参数的纯虚方法。

I have created an abstract base class, which has a pure virtual method with default argument.

class Base {
    ...
    virtual someMethod(const SomeStruct& t = 0) = 0;
    ...
}

class Derived : public Base {
    ...
    virtual someMethod(const SomeStruct& t = 0);
    ...
}

所以我想知道是好的做法是将默认参数设置为纯virutal和整体虚拟方法？

So I would like to know is it a good practice to set the default argument to pure virutal and overall to virtual methods ?

推荐答案

我经常希望使用默认参数和虚函数。其他人正确地指出，这导致歧义，一般不是一个好主意。有一个相当简单的解决方案，我使用。给你的虚拟函数一个不同的名字，使其受保护，然后提供一个公共函数的默认参数调用它。

I often wish to use both default parameters and virtual function as you do. The others have rightfully pointed out however that this leads to ambiguity and is generally not a good idea. There is a reasonably simple solution, one that I use. Give your virtual function a different name, make it protected, and then provide a public function with default parameters which calls it.

class Base {
protected:
    virtual void vSomeMethod(const SomeStruct& t ) = 0;
public:
    void someMethod( const SomeStruc& t = 0 )
    { vSomeMethod( t ); }
}

派生类只需重载 vSomeMethod ，而不必担心默认参数。

Derived classes simply override vSomeMethod and don't worry at all about the default parameters.

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