使用泛型类专门化模板函数

问题描述

我正在将一个简单的数据写入 XML 序列化程序以进行培训.这个想法是将值传递给序列化函数，该函数将执行某些操作将给定值转换为字符串格式.许多类型确实具有内置转换，但对于许多类型，我希望有一个专门的函数来执行此操作.我的方法是:

I am writing a simple data to XML serializer for training purposes. The idea is to pass values to a serialize function that will do something to bring the given values into a string format. Many types do have built in conversions, but for many I want to have a specialized function doing this. My approach is:

我有一个带有此签名的模板函数:

I have a template function with this signature:

template <class T> void serialize(T *value, Serializer *serializer);

我可以像这样专门化模板:

and I can specialize the template like this:

template <> void serialize<bool>(bool *value, Serializer *serializer);

工作正常.现在我想为一个向量编写一个序列化函数，如:

Works fine. Now I want to write a serialize function for a vector, as in:

template <class T> void serialize<std::vector<T*> >(std::vector<T*> *value, Serializer *serializer) {
    serializer->begin_section("array");
    for(std::vector<T*>::iterator it = value->begin(); it != value->end(); it++) {
        serializer->add_value(*it);
    }
    serializer->end_section();
}

但是当我编译它 (g++ 4.6.2) 时，我得到 error: function template partial specialization ‘serialize<std::vector<T*>>' 是不允许的.有没有办法做到这一点?

But when I compile it (g++ 4.6.2), I get error: function template partial specialization ‘serialize<std::vector<T*> >’ is not allowed. Is there a way I can do this?

推荐答案

您的问题是您希望提供模板特化，即模板本身.

Your problem is that you wish to provide a template specialization that is a template itself.

解决问题的最简单方法是根本不使用模板特化，而是依靠函数重载.

The simplest way to resolve your problem is to not use template specialization at all and instead rely on function overloading.

template<class T> void serialize(T *value, Serializer *serializer);

仍然可以提供默认实现，但是如果像

can still provide a default implementation, but if a more specialized version like

void serialize(bool *value, Serializer *serializer);

存在，它将被重载决议首选.这允许您简单地定义一个函数，如

exists, it will be preferred by the overload resolution.This allows you to simply define a function like

template <typename T> void serialize(::std::vector<T> *value, Serializer *serializer);

将调用向量.(考虑到 ::std::vector 比 T 更专业，因此重载决议将在可能的情况下选择此函数).

that will be called for vectors. (Consider that ::std::vector is more specialized than T, so overload resolution will pick this function where it is possible).

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