假设我有两个派生自同一基类的类。我想根据命令行输入实例化一个新的类对象。我能做到这一点:
#include <iostream>
#include "DerivedClass1.h"
#include "DerivedClass2.h"
using namespace std;
int main(int argc, char *argv[])
{
if (argv[1] == "DERIVED CLASS 1") {
DerivedClass1 *myClass = new DerivedClass1(argv[2]);
myClass->doSomething();
} else if (argv[1] == "DERIVED CLASS 2") {
DerivedClass2 *myClass = new DerivedClass2(argv[2]);
myClass->doSomething();
}
}
但我想知道是否有更优雅的方式来做到这一点。我正在考虑创建一个抽象类工厂,或硬编码将字符串名称映射到类实例。 几个限制
1)我的基类是抽象的 - 它包含纯虚函数
2)我只能调用参数化构造函数
答案 0 :(得分:8)
工厂功能应该可以正常工作:
BaseClass* create(std::string const& type, std::string const& arg)
{
// Could use a map or something instead if there are many alternatives
if (type == "DERIVED CLASS 1")
return new DerivedClass1(arg);
else if (type == "DERIVED CLASS 2")
return new DerivedClass2(arg);
else
return nullptr; // Or throw an exception or something else
}
用作
BaseClass* ptr = create(argv[1], argv[2]);