Creating an easy to maintain copy constructor

Question

Consider the following class:

class A {

char *p;
int a, b, c, d;

public:
   A(const &A);
};

Note that I have to define a copy constructor

Answer 1

You really should use smart pointers here.

This would avoid rewriting both the copy constructor and the affectation operator (operator=).

Both of these are error prone.

A common mistake with the operator= is implementing it that way:

SomeClass& operator=(const SomeClass& b)
{
  delete this->pointer;
  this->pointer = new char(*b.pointer); // What if &b == this or if new throws ?

  return *this;
}

Which fails when one does:

SomeClass a;
a = a; // This will crash :)

Smart pointers already handle those cases and are obviously less error prone.

Moreover, Smart pointers, like boost::shared_ptr can even handle a custom deallocation function (by default it uses delete). In practice, I rarely faced a situation where using a smart pointer instead of a raw pointer was unpractical.

Just a quick note: boost smart pointer class, are header-only designed (based on templates) so they don't require additional dependencies. (Sometimes, it matters) You can just include them and everything should be fine.