成员变量和函数参数的模板类型推导 [英] Template type deduction for member variables and function arguments

问题描述

考虑以下模板类的实现:

Consider the following implementation of a template class:

template<class T>
class MyClass
{
public:
    void setVar1(const T& v1)
    {
        var1 = v1;
    }
    void setVar2(const T1& v2)
    {
        var2 = v2;
    }

    T var1;        
    T1 var2;
};

如果模板参数 T 是基本类型(例如 float ， double 或 long double )我想要 T1 = T .

If the template parameter T is a fundamental type (like float, double, or long double) I would like to have T1 = T.

如果模板参数 T 是 std :: complex< float> ，我想使用 T = std :: complex< float> 和 T1 = float .对于 std :: complex< double> 和 std :: complex< long double> .

If the template parameter T is std::complex<float>, I would like to have T=std::complex<float> and T1 = float. Similarly for std::complex<double> and std::complex<long double>.

在模板类型推导

但是，在这种情况下，其他成员函数会阻止使用其解决方案.

However, the additional member functions prevents usage of their solution in this context.

推荐答案

基于Bo Personns的评论以及

Based on Bo Personns comment and the answer provided at https://stackoverflow.com/questions/47334675/template-type-derivation

我有以下工作示例.

.h文件的内容如下.

The content of my .h file is as follows.

#include <iostream>
#include <complex>
#include <typeinfo>


template <typename T>
class MyClass
 {


 template <typename T0>
struct myTypeTraits
 { using type = T0; };

template <typename T0>
struct myTypeTraits<std::complex<T0>>
 { using type = T0; };


public:

   using T0 = typename myTypeTraits<T>::type;

   void setVar1(const T0& v);

   void setVar2(const T& v);


T getVar2() const;




   void print() const;

   T0 var1;
   T  var2;
 };

.cpp文件包含以下代码行.

The .cpp file contains the following lines of code.

template <class T>
void MyClass<T>::setVar1(const T0& v)
{
    var1 = v;
}


template <class T>
void MyClass<T>::setVar2(const T& v)
{
    var2 = v;
}



template <class T>
T MyClass<T>::getVar2() const
{
    return var2;
}


template <typename T>
void MyClass<T>::print() const
{
    std::cout<<"var1: "<<var1<<std::endl;
    std::cout<<"var2: "<<var2<<std::endl;

}



int main()
{

    MyClass<float> tmp;

    MyClass<std::complex<float> > tmp1;

    tmp.print();
    tmp1.print();
    return 0;
}

上面的代码按预期工作.

The above code works as intended.

但是，我在函数返回中的模板类型推导中发布了另一个相关问题输入

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