C/OOP/Library question: object having object member

Using Arduino Programming Questions
1

I'd like to have a class with a private variable "client" which is type of "Client". How do I do this?

First at all I declare the member "Client client;" in the declaration:

// ComEthernetIRC.h
#include "WProgram.h"
#include <Ethernet.h>

class ComEthernetIRC {
  
  public:
    ComEthernetIRC();
    void setup(byte* mac, byte* ip, byte* remoteIp);

  private:
    Client client;
};

But when I try to instantiate an object, I get this error: "Files\arduino-0022\libraries\Ardumote\ComEthernetIRC.cpp:9: error: no match for call to '(Client) (byte*&, int)'"

// ComEthernetIRC.cpp
#include "ComEthernetIRC.h"

ComEthernetIRC::ComEthernetIRC() {
}

void ComEthernetIRC::setup(byte mac[6], byte ip[4], byte remoteIp[4]) {
  Ethernet.begin(mac, ip);
  client(remoteIP, 6667);
}
2

Class constructors can only be called when the instance of that class is created. And as far as I can tell, the Client class provides no other method of assigning its IP and port numbers.

So, you can't define a Client object, and then call it's constructor later to configure it.

3

Depending on what the constructor does, you can

client = Client(a, b);

That would create a new instance of Client and then assign it to the existing instance client.

The other option would be to have a function in the class Client that can set the variables for you.

So you would have a function call at the offending like like this:

client.setVars(a, b);

4

Delta_G:
Depending on what the constructor does, you can

client = Client(a, b);

That would create a new instance of Client and then assign it to the existing instance client.

I tried but it also throws an error: "Ardumote\ComEthernetIRC.cpp.o: In function ComEthernetIRC': C:\Programme\arduino-0022\libraries\Ardumote/ComEthernetIRC.cpp:4: undefined reference to Client::Client()'"

void ComEthernetIRC::setup(byte mac[6], byte ip[4], byte remoteIp[4]) {
  Ethernet.begin(mac, ip);
  client = Client(remoteIP, 6667);
}

The other option would be to have a function in the class Client that can set the variables for you.

It's the arduino ethernet libary's Client class and as jraskell already said it doesn't have a setter method :frowning: (btw. is that bad design? should that be refactored?)

Maybe I could pass a client instance to the setup method... I'll try that...

Edit:
This throws the same "undefined reference to `Client::Client()" error.

void ComEthernetIRC::setup(Client x) {
client = x;
}

5

Will it let you do this in there? Create a new instance and set the one you have equal to it.

There's no copy constructor in the class, so it might default to something that works.

Client temp(remoteIP, 6667);

client = temp;

If it will let you do that, it would have the same effect. temp will go out of scope as soon as you exit the function, but client will be set.

6

The simplest thing is to use the new operator (code for which you have to supply) and then defer creating the instance of Client until you are ready. This compiles:

#include <Ethernet.h>
#include <SPI.h>

// new
void * operator new (size_t size) { return malloc (size); }
// placement new
void * operator new (size_t size, void * ptr) { return ptr; }
// delete
void operator delete (void * ptr) { free (ptr); }

class ComEthernetIRC {
  
  public:
    ComEthernetIRC();
    void setup(byte* mac, byte* ip, byte* remoteIp);

  private:
    Client * client;
};


ComEthernetIRC::ComEthernetIRC() :client (NULL) {
}

void ComEthernetIRC::setup(byte mac[6], byte ip[4], byte remoteIp[4]) {
  Ethernet.begin(mac, ip);
  client = new Client (remoteIp, 6667);
}

void setup ()
{
byte mac[] = {  0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED };
byte ip[] = { 192,168,1,177 };
byte server[] = { 173,194,33,104 }; // Google

 ComEthernetIRC foo;

 foo.setup ( mac, ip, server );
}

void loop () {}
7

[quote author=Nick Gammon link=topic=71559.msg534593#msg534593 date=1315346870]
This compiles:[/quote]

This will take some time for me to learn & understand :slight_smile: however thanks a lot.