Calling member function by pointer - c++11

Question

I'm developing on an ESP32 with vscode and the ESPAsyncWebServer and Wifi libraries.
I'm tring to make my own wifi manager, so I'd like to put some function in a class, but I've some trouble to point to member functions.
I have this definitions without class:
void onNotFound(AsyncWebServerRequest *request){
//Handle Unknown Request
request->send(404);
}
String processor(const String& var)
{
if(var == "HELLO_FROM_TEMPLATE")
return F("Hello world!");
return String;
}
I want to call them from a class witch is:
My_Wifi.h
class My_Wifi {
private:
Config *config;
DNSServer dnsServer;
AsyncWebServer server;
uint16_t serverPort = 80;
void onNotFound(AsyncWebServerRequest *request); <------
String processor(const String& var); <-----
void webServerSetup();
public:
My_Wifi();
void setup(uint16_t port);
void sendJsonDoneResponse(AsyncWebServerRequest *request);
};
My_Wifi.cpp
void My_Wifi::onNotFound(AsyncWebServerRequest *request) {...}
String My_Wifi::processor(const String& var) {...}
void My_Wifi::webServerSetup() {
this->dnsServer.start(53, "*", WiFi.softAPIP());
this->server.onNotFound(this->onNotFound); <------
this->server
.serveStatic("/wifi_settings.html", SPIFFS, "/wifi_settings.html")
.setTemplateProcessor(this->processor) <------
.setFilter(ON_STA_FILTER);
...
}
Obviously this it's only to call the function not to reference it.
How can I call a member function via pointer ?
Thanks for your time.
I tryed:
typedef void (My_Wifi::*onNotFoundFn)(AsyncWebServerRequest *request);
void My_Wifi::webServerSetup() {
this->dnsServer.start(53, "*", WiFi.softAPIP());
onNotFoundFn ptr = &My_Wifi::onNotFound;
this->server.onNotFound(*ptr); //this->server.onNotFound(ptr);
...
}

Answer 1

In order to call member functions, you'll need to supply the object the member function is supposed to be called upon and it should match
typedef std::function<String(const String&)> AwsTemplateProcessor;
Example using a lambda, capturing this:
.setTemplateProcessor([this](const String& str) { return processor(str); } )
A similar lambda for onNotFound which should match
typedef std::function<void(AsyncWebServerRequest *request)> ArRequestHandlerFunction;
would look like this:
server.onNotFound([this](AsyncWebServerRequest* r) { onNotFound(r); });
Since you do not actually use this in your onNotFound callback, you could make your current callback function static:
class My_Wifi {
private:
static void onNotFound(AsyncWebServerRequest *request);
and supply that without a lambda:
server.onNotFound(&My_Wifi::onNotFound);
Alternatively, do not create a member function at all. Just supply a lambda:
server.onNotFound([](AsyncWebServerRequest* request){ request->send(404); });