C++获取对象类型

发布于 2024-12-11 22:12:15 字数 614 浏览 0 评论 0原文

我有一个 C++ 应用程序，它具有以下类：

class AAA
class BBB 继承自 AAA
class CCC 继承自AAA
class DDD 继承自 CCC

（所有类都标记为 public）

现在我有以下地图：

map <DWORD, AAA*>

我在中找到一个 AAA 对象map，由DWORD id组成，但现在我想知道AAA的类型是什么：

这将是逻辑：

if(AAA is BBB)
{
...
}
if(AAA is CCC)
{
...
}
if(AAA is DDD)
{
...
}

你知道吗如何用C++编写它（不添加getType()多态函数）？

原文

I have a C++ application which has the following classes:

class AAA
class BBB inherits from AAA
class CCC inherits from AAA
class DDD inherits from CCC

(All of the classes are marked as public)

Now I have the following map:

map <DWORD, AAA*>

I find an AAA object in the map, by a DWORD id, but now I want to know what is the type of AAA:

this will be the logic:

if(AAA is BBB)
{
...
}
if(AAA is CCC)
{
...
}
if(AAA is DDD)
{
...
}

Do you know how to write it in C++ (without adding a polymorphic function of getType())?

分享到QQ

分享到微博

如果你对这篇内容有疑问，欢迎到本站社区发帖提问参与讨论，获取更多帮助，或者扫码二维码加入 Web 技术交流群。

发布评论

需要登录才能够评论，你可以免费注册一个本站的账号。

智商已欠费 2024-12-18 22:12:15

要求这样做表明您的做法是错误的。您正在尝试复制虚拟方法的发明目的。只需在基类中添加一个虚拟方法即可。

class AAA
{
public:
    virtual void DoSomething() = 0;
}

class BBB : public AAA
{
public:
    void DoSomething() { ... }
}

class CCC : public AAA
{
public:
    void DoSomething() { ... }
}

class DDD : public AAA
{
public:
    void DoSomething() { ... }
}

在你的调用代码中，你的逻辑很简单：

// no need for if() blocks. it's the point of virtual methods.
AAA* somePointer;
...
somePointer->DoSomething();

我意识到你可能不能只是将当前的“dosomething”代码复制/粘贴到其中。但这是您应该在这种情况下使用的模式。也许使用像 GetSomeInfo 这样的东西代替 DoSomething 更有意义，调用者可以用它来做任何需要做的事情。此模式的具体用法取决于您的上下文。

Requiring this indicates you are doing it the wrong way. You are trying to replicate something that virtual methods were invented for. Just put a virtual method in your base class.

class AAA
{
public:
    virtual void DoSomething() = 0;
}

class BBB : public AAA
{
public:
    void DoSomething() { ... }
}

class CCC : public AAA
{
public:
    void DoSomething() { ... }
}

class DDD : public AAA
{
public:
    void DoSomething() { ... }
}

And in your calling code, your logic is simple:

// no need for if() blocks. it's the point of virtual methods.
AAA* somePointer;
...
somePointer->DoSomething();

I realize you maybe can't just copy / paste your current "dosomething" code into this. But this is the pattern you should be using for this scenario. Perhaps instead of DoSomething it makes more sense to have something like GetSomeInfo, that the caller can use to do whatever it needs to do. The specific usage of this pattern depends on your context.

回复收藏 0 原文