How to give a instance a function from a library in C? - c++

Question

I wanted to give the aRest library
a function to expose to the api.
But I am importing a customlibrary,
I wanted to give the aRest instance a function in that library.
This is my code
#include <ESP8266mDNS.h>
#include <ESP8266WiFi.h>
#include <aREST.h>
#include <EEPROM.h>
#include <WiFiClient.h>
//My Custom Made C/C++ Libraries
#include <DeviceEeprom.h>
#include <DeviceRoute.h>
//Creating my customLib instances
DeviceEeprom deviceEeprom = DeviceEeprom();
DeviceRoute deviceRoute = DeviceRoute();
// Create aREST instance
aREST rest = aREST();
int myFunction();
void setup()
{
Serial.begin(115200);
rest.set_id("1");
rest.set_name("esp8266");
rest.function("myFunction" &myFunction);
}
void loop()
{
}
int myFunction()
{
return 1;
}
I wanted to go from this.
rest.set_function("myFunction" &myFunction);
To this.
rest.set_function("myFunction" deviceRoute.myFunction());
UPDATE
I found the rest.function() code
This is the code
void function(char * function_name, int (*f)(String)){
functions_names[functions_index] = function_name;
functions[functions_index] = f;
functions_index++;
}
Mayby this helps out?

Answer 1

There's no way to pass a pointer to a non-static member function directly to aREST::function.
Non-static member functions are different than static member functions and freestanding functions. They require an object to work on. That means that &DeviceRoute::myFunction is not compatible with the type int(*)(String). Instead it's a int (DeviceRoute::*)(String).
To make this work, you need a static or freestanding wrapper function that calls the member function you want. Since aREST::function doesn't accept any sort of context pointer, your only real option is to use a global variable:
//Creating my customLib instances
DeviceEeprom deviceEeprom;
DeviceRoute deviceRoute;
// Create aREST instance
aREST rest;
int myFunction(String s)
{
return deviceRoute.myFunction(s);
}
void setup()
{
Serial.begin(115200);
rest.set_id("1");
rest.set_name("esp8266");
rest.function("myFunction" &myFunction);
}
void loop()
{
}