I wish to introduce some additional (and general) functional to an existing (and foreign) freepascal's unit.
With C++'s multiple inheritance quality it is easy to implement: ---
#include <stdio.h>
#include <list>

using namespace std;
class TObj {
protected:
	int fff;
};
class TObj2: TObj {
protected:
	int fff2;
};
class TIntf {
public:
	virtual void ppp() = 0;
};
class TObji: public TIntf,TObj {
public:
	virtual void ppp();
};
class TObj2i: public TObji,TObj2 {
public:
	virtual void ppp();
};

void TObji::ppp()
{

	printf("111 %p\n",this);
	fff = 111;

}

void TObj2i::ppp()
{
	printf("222 %p\n",this);
	fff2 = 222;
	TObji::ppp(); // like "inherited" in pascal
}
typedef list<TIntf*> myList;

int main(void)
{

	myList l;
	l.push_back(new TObji);
	l.push_back(new TObj2i);
	for (myList::iterator i = l.begin(); i != l.end(); ++i)
		(*i)->ppp(); // general interface used

}
---
TObj,TObj2 - the basic classes from foreign module TObji,TObj2i - my additional functional implementation

But i can't invent nothing like that (except the some procedural hack with pointers substitution), in object pascal, with him interfaces! Can somebody direct me to some object-style variant, maybe objfpc relieve here (now i use delphi mode) ?