Calling member function by pointer-CodePudding

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);
  ...
}

CodePudding user response：

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); });