C ++专业化模板类函数而不复制代码 [英] C++ specialize template class function without duplicating code

问题描述

我想写5个不同的类，每个类都有很多成员函数，除了一个，这是每个类都是特殊的。我可以写这个避免代码重复吗？

I want to write 5 different classes, each of which has many member functions which are exactly the same, except of one, which is special for each class. Can I write this avoiding code duplication?

注意，
Aleksejs

Regards, Aleksejs

我的代码的版本，它抛出错误：

Below is a very shortened version of my code, which throws the error:

template_test.cpp:15:35: error: invalid use of incomplete type ‘class impl_prototype<cl, 1>

---

---

#include <iostream>
using namespace std;

template <int cl, int dim>
class impl_prototype {
public:
  impl_prototype() {}

  int f(int x) { return cl + 2 * g(x); }
  int g(int x) { return cl + 1 * x;}

};

template <int cl>
int impl_prototype<cl, 1>::g(int x) { return cl + 3 * x; }

int main ()
{
  impl_prototype<0, 0> test_0;
  impl_prototype<0, 1> test_1;


  cout << test_0.f(5) << " " << test_0.g(5) << std::endl;
  cout << test_1.f(5) << " " << test_1.g(5) << std::endl;


  return 0;
}

推荐答案

，例如：

template <int cl, int dim>
class impl_prototype
{
    int g(int x, std::integral_constant<int, 1>) { return cl + 3 * x; }

    template <int I>
    int g(int x, std::integral_constant<int, I>) { return cl + 1 * x; }

public:
    int f(int x) { return cl + 2 * g(x); }
    int g(int x) { return g(x, std::integral_constant<int, dim>());}
};

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