我有一个抽象类，它的变量owner_是一个字符串。每个派生类都声明此变量的名称。将变量包含在抽象基类中是更好的做法，还是可以在派生类中更好地多次实现它？
#include <string>
#include <iostream>
class Pet
{
public:
Pet(const std::string& owner) : owner_(owner) {}
virtual ~Pet() = 0;
virtual void print_status() = 0;
protected:
const std::string owner_;
};
Pet::~Pet() {}
class Dog : public Pet
{
public:
Dog(const std::string& owner) : Pet(owner) {}
~Dog() {};
void print_status()
{
std::string s = "Woof! My owner is ";
s += owner_;
std::cout << s << std::endl;
}
// Or better here?
// private:
// const std::string owner_;
};
class Cat : public Pet
{
public:
Cat(const std::string& owner) : Pet(owner) {}
~Cat() {};
void print_status()
{
std::string s = "Meow! My owner is ";
s += owner_;
std::cout << s << std::endl;
}
// Or better here?
// private:
// const std::string owner_;
};
int main()
{
Dog dog("Mario");
dog.print_status();
Cat cat("Luigi");
cat.print_status();
return 0;
}
IMO正是抽象基类的用途：为继承层次结构中的接口提供通用实现。
我将更进一步，甚至将接口与抽象基类分开：
struct IPet {
virtual ~IPet() = {}
virtual void print_status() = 0;
virtual const std::string& get_owner() const = 0;
};
class Pet : public IPet
{
public:
Pet(const std::string& owner) : owner_(owner) {}
virtual const std::string& get_owner() const { return owner_; }
virtual ~Pet() {} // = 0; Don't declare the destructor as pure virtual function
virtual void print_status() = 0;
protected:
std::string owner_;
};
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我来说两句