how to make a list of template abstract class - c++

Question

I must to do a list of template abstract base classes (and I have the delivered classes too)
but I don't can inizialize the element of my list because the element is an abstract class...
this is my declaration:
/* fsm (list node) declaration */
template<class step_type> class fsm {
protected:
step_type step;
step_type step_old;
step_type step_tmp;
char name[256];
fsm *next;
fsm *prev;
public:
fsm(step_type step);
virtual void update() = 0;
void show(){cout << step << ' ' << step_tmp << '\n'; };
void init(step_type st_current) {step = st_current;};
//metodi per gestione nodo lista
step_type getStep() { return step; }
fsm* getNext() { return next; }
fsm* getPrev() { return prev; }
void setStep(step_type s) { step = s; }
void setNext(fsm *n) { next = n; }
void setPrev(fsm *p) { prev = p; }
};
/* fsm_List declaration */
template <class step_type>
class fsm_List
{
fsm<step_type> *head, *tail;
int size;
public:
fsm_List();
fsm<step_type>* getHead() { return head; }
fsm<step_type>* getTail() { return tail; }
int getSize() { return size; }
void insert(fsm<step_type> *n); // add node to list
void insert(step_type &value); // new node and add in list
fsm<step_type> *search(step_type &value); //first node with value
void delnode(fsm<step_type> *n); // remove node
int delvalue(step_type &value); // remove all nodes
};
this is my delivered class:
class deri_pinza : public fsm<pin_steps>{
private:
bool cmd_prelevamento_done;
public:
deri_pinza(): fsm<pin_steps>(ST_PIN_BOOT){
cmd_prelevamento_done = false;
};
void update();
};
where:
enum pin_steps {
ST_PIN_BOOT,
ST_PIN_CHECK_MOTORE,
ST_PIN_ZERO_MOTORE,
ST_PIN_WAIT_ZERO_MOTORE,
ST_PIN_OPEN,
ST_PIN_READY,
};
I have tryed to test in my main, but it's wrong...
fsm<pin_steps> *one, *two, *three, *four, *five;
one = new fsm<pin_steps>(ST_PIN_CHECK_MOTORE);
two = new fsm<pin_steps>(ST_PIN_ZERO_MOTORE);
three = new fsm<pin_steps>(ST_PIN_WAIT_ZERO_MOTORE);
four = new fsm<pin_steps>(ST_PIN_OPEN);
five = new fsm<pin_steps>(ST_PIN_READY);
fsm_List<pin_steps> *mylist = new fsm_List<pin_steps>();
(*mylist)+=(*one);
(*mylist)+=(*two);
mylist->insert(one);
mylist->insert(two);
cout << *mylist << endl;
how can I inizialize the List without inizialize fsm ( abstract class)?

Answer 1

you can't create an instance of fsm<> with new, since it's abstract - it contains the pure virtual method virtual void update()=0;
you can for example:
fsm<pin_steps> *one...
one = new deri_pinza;
this is legal - and go on from here...
EDIT - followup to our comments:
if you need a more general deri pinza (a generic one), it can be defined as:
template <typename STEP_TYPE>
class deri_pinza_gen : public fsm<STEP_TYPE> {
private:
bool cmd_prelevamento_done;
public:
deri_pinza_gen(STEP_TYPE step) : fsm<STEP_TYPE>(step){
cmd_prelevamento_done = false;
};
virtual void update();
virtual ~deri_pinza_gen();
};
and then:
mylist->insert( new deri_pinza_gen<pin_steps>(ST_PIN_BOOT) );
mylist->insert( new deri_pinza_gen<pin_steps>(ST_PIN_CHECK_MOTORE) );
ANOTHER_list->insert( new deri_pinza_gen<ANOTHER_pin_steps>(ANTHER_enum_item) );
...
are valid insertions. I have declared update() virtual here, so you can derive your deri_pinza from this one, if you need it.