copying unknown datatypes

I have a variable in a templated class (A) that I want to be able to change from a wrapper class (B). The data type of A changes with each instance (string, int, float...), but what I'm wondering is if I can create a universal member function in B that will set the value in A?
would it be possible to

a = malloc(sizeof(*newVal));
strcpy(a, newVal);

where

template <class T>
class A
{
public:
T * a;
}

and

void * newVal;

is this possible? and am I making sense?

First of all, the obvious question is: Why do you change a variable in class A in a function in class B? This violates the encapsulation priciple of OOP, so if there is no good reason to do this, you should consider a redesign. A better way would be to have accessor functions in class A, which can be used by class B. Something along the lines of

Code:

---

template <class T>
class A
{
// ..
public:
  T &get_Data() // should probably be const
  {
    return a;
  }
  void put_Data(const T &src)
  {
    a = src;
  }
// ...
};

---

Ok, so what if you really have a good reason to violate this? Then you could make your member function in B also a template, if you have a compiler that supports member template functions. The code would be:

Code:

---

class B
{
// ...
public:
  template <class T>
  void ChangeA(A<T> &val)
  {
    val.a = T();
  }
// ...
};

---

you're right again...
first way is the best, thanks