C++: Throwing an exception invokes the copy constructor?

Question

We have an custom error class that is used whenever we throw an exception:

class AFX_CLASS_EXPORT CCLAError : public CObject

It has the fol

Answer 1

It appears that you have misunderstood what re-throw means. When you do -

catch(CCLAError& e)
{
   throw e;
}

-- you are NOT rethrowing. Instead, as you have observed, you are indeed creating a copy of the new exception. Instead (again, as you have found for yourself), this is what is technically the correct way to re-throw:

catch(CCLAError& e)
{
   throw;
}

Read chapter 14 in Stroustrup's TC++PL (14.3.1 deals with rethrowing).

Also, you do NOT have to do -

throw new CCLAError( ... )

Instead, do -

throw CCLAError( ... )

-- like you were doing before, only receive by CONST reference (you cannot hold a reference to a temporary).

catch(const CCLAError &e)