Question

我有几个客户端代码必须执行if检查的实例，如下所示：

void Client::Method1()
{
    if (flag is true)
    {
        m_Object.DoSomething();
    }
    else
    {
        m_Object.DoSomethingElseInstead();
    }
}

void Client::Method2()
{
    if (flag is true)
    {
        m_Object.DoSomething2();
    }
    else
    {
        m_Object.DoSomethingElseInstead2();
    }
}

void Client::Method3()
{
    if (flag is true)
    {
        m_Object.DoSomething3();
    }
    else
    {
        m_Object.DoSomethingElseInstead3();
    }
}

等等......

我想封装if（标志）检查，如果可能的话，以某种方式在m_Object内部处理。我想过使用PIMPL习惯用法，但我真正需要的是以某种方式封装这种行为。有更简单的方法吗？

Answer 1

您可以使用strategy pattern。类似的东西：

class Strategy
{
public:
    virtual ~Strategy() = default;
    virtual void Method1() = 0;
    virtual void Method2() = 0;
    virtual void Method3() = 0;
};

class Strategy1 : public Strategy
{
public:
    explicit Strategy1(Client& client) : client(client) {}
    void Method1() override {client.m_Object.DoSomething();}
    void Method2() override {client.m_Object.DoSomething2();}
    void Method3() override {client.m_Object.DoSomething3();}
private:
    Client& client;
};

class Strategy2 : public Strategy
{
public:
    explicit Strategy2(Client& client) : client(client) {}
    void Method1() override {client.m_Object.DoSomethingElseInstead();}
    void Method2() override {client.m_Object.DoSomethingElseInstead2();}
    void Method3() override {client.m_Object.DoSomethingElseInstead3();}
private:
    Client& client;
};

class Client
{
public:
    Client() { SetFlag(true); }
    void Method1() { strategy->Method1(); }
    void Method2() { strategy->Method2(); }
    void Method3() { strategy->Method3(); }

    void SetFlag(bool flag) // or better: SetStrategy
    {
        if (flag) {
            strategy = std::make_unique<Strategy1>(*this);
        } else {
            strategy = std::make_unique<Strategy2>(*this);
        }
    }
private:
    std::unique_ptr<Strategy> strategy;
    Object m_Object;
};

Answer 2

我会这样做：

m_Object.DoSomething1(flag); // or
m_Object.DoSomething2(flag); // or
m_Object.DoSomething3(flag);

例如，DoSomething1的实施将是：

Object::DoSomething1(bool flag)
{
    if (flag)
    {
        // Something here.
    }
    else
    {
        // Something else here.
    }
}

不会使代码更实用，但仍然非常简单易读，并且您将标志进一步检查（循环）。

在类中封装几个if语句的最简单方法是什么？

2 个答案: