Cannot extend C template class by additional parameter-CodePudding

I'm beginner in C templates and I cannot inherit my derived class from base one with additional parameter. I have base class:

// idproc.h file
#include <array>

using namespace std;
template<class T, int numGroups>
class BaseSequence
{
public:
    int m_numGroups;
    array<T, numGroups> m_groups;
    int m_currPos;

public:
    BaseSequence() : m_numGroups(numGroups), m_currPos(0) {
        std::fill(begin(m_groups), end(m_groups), T());
    }
    virtual string PrintSequence() {
        string identifier;
        for (auto &&group : m_groups)
        {
            identifier  = to_string(group)   "-";
        }
        identifier.pop_back();
        return identifier;
    }
};

My derived class is :

template<class T, int numGroups, int maxVal>
class IdentifierSequence : BaseSequence<T, numGroups> 
{
    int m_maxVal;
public:
    using BaseSequence<T, numGroups>::PrintSequence;
    IdentifierSequence(int maxVal): m_maxVal(maxVal) {}; // compiler error
};

As you can see my IdentifierSequence has additional parameter called m_maxVal, I need to initialize it in constractor.

I'm using it by following way:

// main.cpp file
    
#include <iostream>
#include "idproc.h"

int main(int argc, char** argv) {

    IdentifierSequence<int, 10, 2> is;
    std::cout << is.PrintSequence() << std::endl;

    return 0;
}

Please explain me how to fix this problem.

CodePudding user response：

Your template parameter and constructor accept two variables named maxVal, so you have ambiguity error. You should change the name of either of them.

template<class T, int numGroups, int maxVal_templ> // note: maxVal -> maxVal_templ
class IdentifierSequence : BaseSequence<T, numGroups> 
{
    int m_maxVal;
public:
    using BaseSequence<T, numGroups>::PrintSequence;
    IdentifierSequence(int maxVal): m_maxVal(maxVal) {};
};

CodePudding user response：

Remove the parameter from the constructor, like so:

IdentifierSequence(): m_maxVal(maxVal) {}

Then it will compile.

You can access maxVal directly, no need to pass it to the constructor.

If the value is never changed during execution, you don't even need m_maxVal, depending on your usage. You can use the template parameter anywhere in the class.