Tuple of Jsoncpp functions-CodePudding

I am currently working with some config files, and I wanted to map options with configuration functions. So far, I have this working code:

std::unordered_map<std::string, void (Model::*)(int)> m_configMap = 
{
{ "threshold", &Model::setThreshold }
};

Now, as you may very well notice, this approach would not work if the input parameters were different, so I thought of adding the a parser like so (with the Jsoncpp library):

std::unordered_map<stsd::string, std::tuple<void(Model::*)(std::any), std::any(Json::Value*)()>> m_configMap = 
{
{ "threshold", {&Model::setThreshold, &Json::Value::asInt}}
};

Now, this did not work,as it was giving me an error in the brace initialiser list saying that it could not convert types. I didnt quite understand, so I tried an smaller example:

std::tuple<void(Model::*)(int), Json::Int (Json::Value::*)(void)> foo =
{&Model::setThreshold, &Json::Value::asInt };

And this is not working either. However, if I change the Json part for a string, it will work.

I am not sure of what is wrong with this, and I was wondering if someone saw something that I'm missing.

Thank you very much in advance

CodePudding user response：

Looks like you're not refering to an instance of Model, or the member function of Model is not static. I don't know about the JSON part but this should get you started. If you have questions let me know.

#include <iostream>
#include <functional>
#include <string_view>
#include <unordered_map>

struct Model
{
public:
    void setTreshold(int value)
    {
        std::cout << "treshold set to " << value << "\n";
    }

};


int main()
{
    Model model;

    // I prefer using string_view over string for const char* parameters
    // I also prefer using std::function over function pointers
    std::unordered_map<std::string_view, std::function<void(int)>> m_configMap
    {{
        // the function should refer to an instance of Model, so  use a lambda 
        // not a direct function pointer
        {"threshold", [&](int value) { model.setTreshold(value); } }
    }};

    auto fn = m_configMap["threshold"];
    fn(42);

    return 0;
}