use of deleted function 'ESP8266WebServer

[seamiki]

just a small update for the WebSocket example ESP8266/Examples/14. WebSocket/A-WebSocket_LED_control/A-WebSocket_LED_control.ino fails to compile showing following errror in the arduino ide:

use of deleted function 'ESP8266WebServer::ESP8266WebServer(const ESP8266WebServer&)'

To fix, replace line 11 ESP8266WebServer server = ESP8266WebServer(80); with ESP8266WebServer server (80); Thanks for the excellent tutorial I made a PR but i'm not sure if it is appropriate: git is new for me.

[tttapa]

This is because the copy constructor was deleted in release v2.4.0 of the Arduino Core. The solution you proposed is indeed correct.

[facetime88]

How do I can declare it within a custom class. ESP8266WebServer server(80); will not working.

[dashiva91]

How do I can declare it within a custom class. ESP8266WebServer server(80); will not working.

Could you tell what are the issues? If you declare it as a class member, you need to initialize port number with initialization list instead of constructor.

[b4dnewz]

it's possible to initialize the server as private (or public) property of a class?

class SetupServer {
  // ESP8266WebServer server(80);

  public:
    SetupServer(int port = 80) {
      // init server using custom port
    };
};

I'm not very familiar with c++ and i've tried different ways without success, any hint?

thank in advance.

[mszekiel]

I'm not very familiar with c++ and i've tried different ways without success, any hint?

thank in advance.

Hi. Did you solve this? I'm actually in quite similar point.

[b4dnewz]

@mszekiel nope..

I think the solution is in @dashiva91 answer:

If you declare it as a class member, you need to initialize port number with initialization list instead of constructor.

but I'm not sure how to implement it

[tttapa]

You cannot initialize the member like that. It's just a declaration, not a call to the constructor. You can provide a default value, though, but you cannot use direct initialization.
The default value will be used to initialize the member in the constructor when no other initialization is specified. This is the important bit: initialization happens in the constructor, not at the declaration of the member.

This will not work:

class SetupServer {
  private:
    ESP8266WebServer server(80); // <-- Trying to call constructor ESP8266WebServer::ESP8266WebServer(int)
};

This is better:

class SetupServer {
  public:
    SetupServer() = default; // <-- `server` is implicitly initialized to ESP8266WebServer{80} here
    SetupServer(int port) : server{port} {} // <-- Default value is ignored here

  private:
    ESP8266WebServer server = {80};  // <-- Declaration with default value using list initialization
};

Note the use of an initializer list to initialize server in SetupServer::SetupServer(int).

In this case, you could just leave out the default value entirely, because there is only a single constructor that uses it.

class SetupServer {
  public:
    SetupServer(int port = 80) : server{port} {}

  private:
    ESP8266WebServer server;
};

If you had different constructors that needed the default value, the previous snippet would be bad, because you would have to repeat yourself:

class SetupServer {
  public:
    SetupServer(int port = 80) : server{port} {}
    SetupServer(string name) : server{80}, name{name} {} // <-- repetition of default value

  private:
    ESP8266WebServer server;
   string name;
};

This would be better:

class SetupServer {
  public:
    SetupServer() = default; // <-- `server` is implicitly initialized to ESP8266WebServer{80} here
    SetupServer(int port) : server{port} {} // <-- Default value is ignored here, name is default initialized to string{}
    SetupServer(string name) : name{name} {} // <-- `server` is implicitly initialized to ESP8266WebServer{80} here as well

  private:
    ESP8266WebServer server = {80};  // <-- Declaration with default value using list initialization
    string name;
};

Some more links:

• Member initialization
• List initialization
• Initializer list

[b4dnewz]

@tttapa dude that's great! this evening i'm going to study some of these links many many thanks

[tttapa]

The links to cppreference contain a lot of information, don't try to understand everything on your first read. Especially the special cases and the different behaviour between C++ versions (the ESP8266 Core uses C++11 - don't ask me why).
Try to focus on the general explanation and the examples.