使用指针或引用时的模板专业化优先级

发布于 2024-10-06 19:58:30 字数 1035 浏览 1 评论 0原文

我有一个像这样的 Serializer 类：

class Serializer
{
public:
    // Func 1 (default)
    template <class T>
    void Serialize(T* pValue)
    {
        SerializeInternal(reinterpret_cast<char*>(pValue), sizeof(*pValue));
    }

    // Func 2 (specialization)
    template <> 
    void Serialize<Serializable>(Serializable* pSerializable)
    {
        pSerializable->Serialize(*this);
    }

protected:

    // Implemented by input and output serializers
    virtual void SerializeInternal(char* pData, size_t size) = 0;
};

现在我的问题是，当我有继承 Serialized 接口的类时，它们将始终由 Func 1 处理，即使我希望它们由 Func 2 处理（指针或引用并不重要，它们两者行为相同）。似乎 C++ 无法识别 Serialized 接口是继承的，除非您明确指定：

SerializableClass sc; // Inherits Serializable
InputSerializer s; // Inherits Serializer

s.Serialize(&sc); // Func 1 is called >:(
s.Serialize<Serializable>(&sc); // Func 2 is called

现在，只要我忘记在某处添加，程序当然就会出错，这很漂亮恼人的。

有什么办法解决这个问题吗？

原文

I have a Serializer class like this:

class Serializer
{
public:
    // Func 1 (default)
    template <class T>
    void Serialize(T* pValue)
    {
        SerializeInternal(reinterpret_cast<char*>(pValue), sizeof(*pValue));
    }

    // Func 2 (specialization)
    template <> 
    void Serialize<Serializable>(Serializable* pSerializable)
    {
        pSerializable->Serialize(*this);
    }

protected:

    // Implemented by input and output serializers
    virtual void SerializeInternal(char* pData, size_t size) = 0;
};

Now my problem is when I have classes that inherit the Serializable interface they will always be handled by Func 1, even though I want them to be handled by Func 2 (pointers or references doesn't matter they both behave equally). It seems like C++ doesn't recognize that the Serializable interface is inherited unless you clearly specify that:

SerializableClass sc; // Inherits Serializable
InputSerializer s; // Inherits Serializer

s.Serialize(&sc); // Func 1 is called >:(
s.Serialize<Serializable>(&sc); // Func 2 is called

Now as soon as I forget to add <Serializable> somewhere the program of course bugs out, which is pretty annoying.

Is there any way around this?

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十级心震 2024-10-13 19:58:30

除非您明确指定，否则 C++ 似乎无法识别 Serialized 接口是继承的

这是 true。如果您有某个类，则

class SerializableClass : public Serializable

在推导 T 参数时仅考虑 SerializedClass，而不是 Serialized。

如果您需要创建两个函数，一个函数采用任何指针，另一个函数采用指向从 Serialized 派生的任何对象的指针，您可以创建两个重载，并在可能的情况下使用 SFINAE 选择较窄的一个。

template <class T>
typename boost::enable_if_c<!boost::is_base_of<Serializable, T>::value, void>::type foo(T*) { ... }

template <class T>
typename boost::enable_if<boost::is_base_of<Serializable, T>, void>::type foo(T*) { ... }

如果您不想使用 boost，您可以实现类似于this 的所需功能。

It seems like C++ doesn't recognize that the Serializable interface is inherited unless you clearly specify that

This is true. If you have some class

class SerializableClass : public Serializable

only SerializableClass, not Serializable, is considered when deducing the T parameter.

If what you need is create two functions, one taking any pointer, the other taking a pointer to anything derived from Serializable, you can create two overloads and use SFINAE to select the narrower one when possible.

template <class T>
typename boost::enable_if_c<!boost::is_base_of<Serializable, T>::value, void>::type foo(T*) { ... }

template <class T>
typename boost::enable_if<boost::is_base_of<Serializable, T>, void>::type foo(T*) { ... }

If you don't want to use boost, you can implement required functionality akin to this.

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