pimpl implementation

[Braniac0]

Hi, I am trying to implement a pimpl implementation, but seem to have a problem.
This is the header Record.h

#include <iostream>
#include <string>
#include <vector>

using namespace std;
class RecImpl;
class Record{
	public:
		Record(string t);
		~Record();
		int getId();
		string getTitle();
		friend ostream & operator <<(ostream &os, Record &r);
		friend istream& operator>> (istream &in, Record &r);

	private:
		RecImpl* pimpl;
};

This is the record implemantation, RecImpl.ccp

#include "Record.h"
static int movieID = 0;

class RecImpl{
	public:
		RecImpl(string t): title(t), id(movieID++){
			cerr << "create " << id << endl;
		}
		~RecImpl(){
			cerr << "DELETING  " << id << endl;
		}
		int getId(){
			return id;
		}
		string getTitle(){
			return title;
		}
	private: 
		string title;
		int id;
};

But when i start the Record.ccp file

#include "Record.h"
Record:: Record(string t){
	pimpl=new RecImpl(t);
}

I get and error where i underlined, saying that incomplete type is not allowed. Can anyone tell me what what i'm missing? Thanks

[andywestken]

new needs to see the definition of RecImpl.

One solution would be, of course, to move the RecImp class definition into a header and include RecImp.h in Record.cpp, too. But that would prob be the wrong move here as it will expose RecImpl too widely.

Instead you could provide a factory function.

1. Add the following to RecImpl.cpp after the class definition

RecImpl* CreateRecImpl(string t){
	RecImpl* pimpl=new RecImpl(t);
	return pimpl;
}

2. Create a new header with just the function definition

// RecImpl.h

class RecImpl;

extern RecImpl* CreateRecImpl(string t);

3. And then modify Record.cpp to use the factory function

#include "Record.h"
#include "RecImpl.h"

Record::Record(string t){
	pimpl=CreateRecImpl(t);
}

[Braniac0]

Thanks alot, works now!