Advice needed :How to avoid duplicate code?

Projects Programming
1

Hi all,

I am trying to avoid writing code for the same thing twice. For example consider:

   Serial.print ("Free RAM: ");Serial.print (freeRam());
   Serial.print ("IP Address : ");PrintIPAddress(IP);
   Serial.print ("Subnet Mask : ");PrintIPAddress(subnet);
   Serial.print ("Gateway ");PrintIPAddress(gateway);
   Serial.print ("Dns : ");PrintIPAddress(DNS);

and :

   client.print ("Free RAM: ");client.print (freeRam());
   client.print ("IP Address : ");PrintIPAddress(IP);
   client.print ("Subnet Mask : ");PrintIPAddress(subnet);
   client.print ("Gateway ");PrintIPAddress(gateway);
   client.print ("Dns : ");PrintIPAddress(DNS);

Is there a way of avoiding writing two separate functions for the above? In other words is it possible to re-direct the output from Serial to client without adding more code for the same functionality?

Thanks for your help..

2

First of all...how does PrintIPAddress know to print through serial or client?

just make 2 functions for each of those and call the functions instead...

3

First of all...how does PrintIPAddress know to print through serial or client?

For now PrintIPAddress only prints through Serial. I am looking at ways to make it also print through client without writing an entirely separate function. The same applies for other functions as well. The above is only an example.

4

The only way I can think of doing that would be to make a function with a type of parameter, but the object types would need to be the same, but they are not...so you would need a new class, but from here it gets completely pointless...so I got nothing...

5

I was also thinking that maybe I could pass a parameter to a function which would somehow determine where the output goes. But then couldn't figure out how to actually do it from there.

Thanks for your help anyhow :slight_smile:

6

In C++, you would do this using a polymorphic class:

class PrintThing {
  public:
    virtual void prints(char *);
    virtual void printi(int);

    void info() {
      prints ("Free RAM: ");
      printi(1);
      prints ("IP Address : ");
      printi(2);
      prints ("Subnet Mask : ");
      printi(3);
      prints ("Gateway ");
      printi(4);
      prints ("Dns : ");
      printi(5);
    }

};

class PrintToSerial : public PrintThing {
    void prints(char *s) {
      Serial.print(s);
    }
    void printi(int i) {
      Serial.print(i);
    }
} printToSerial;

class PrintToClient : public PrintThing {
    void prints(char *s) {
      /* implementation of client.prints */
    }
    void printi(int i) {
      /* implementation of client,printi */
    }
} printToClient;

void someFunction() {
  printToSerial.info();
  // or
  printToClient.info();

  // or choose a printer based on a boolean value

  PrintThing *thePrinter;
  if (1 > 2) {
    thePrinter = &printToSerial;
  }
  else {
    thePrinter = &printToClient;
  }

  thePrinter->info();
  thePrinter->prints("\n ==== END OF PRINTING ===\n");

}

Your client printer probably needs to take a "client" pointer in its constructor, and to save that value in a class variable.

7

Maybe something like this

const Stream * streams[] = { &Serial, &client };

...
template <typename T> void printToStreams( T val );
template <typename T> void printToStreams( T val )
{
  Stream * stream;
    
  for ( uint8_t i = 0; i < sizeof( streams ) / sizeof( Stream * ); i++)
  {
    stream = (Stream *) streams[i];
    stream->println( val );
  }
}

...

printToStreams( "Free RAM: " );
printToStreams( freeRam() );
...
8

Thank you all for your input.

9

You guys are over-complicating this. Both HardwareSerial and EthernetClient extend the Print class, which has the print and println methods. Just make your functions take a reference to an instance of the Print class.

10

Could you give an example christop?

11

I'm on my phone so I can't test this example, but it should look something like this:

void printIt(Print& p)
{
    p.println("whatever");
}

Edit to add:

Then call it like this:

printIt(Serial);
printIt(client);
12

I will sure give it a try! Thanks

13

Success! Works perfect christop. Simple and easy.!

Thanks a lot!