Chapter 1

If the new(ELeave) fails, then iObject2 is still pointing to the previously allocated object,
even though that object has been deleted. The result is going to be a double-deletion error,
one way or another.
Important
When reallocating, you must always zero the pointer after delete and
before new.
The code should have been
case EMagicCmdNew2:
delete iObject2;
iObject2 = NULL;
iObject2 = new(ELeave) CX;
iEikonEnv->InfoMsg(_L("New 2"));
break;
Once again, there is no need to set pointers to zero after a delete in the destructor
because there is no chance that the pointer will ever be used again. But at all other times, if
you delete something, you should zero its pointer immediately.
6.2.5 How Does Leave Work?
The User::Leave() function causes execution of the active function to terminate, and on
through all calling functions, until the first function is found that contains a TRAP() or
TRAPD() macro.
User::Leave() is defined in e32std.h; you pass a single 32-bit integer error code.
class User
{
public:
IMPORT_C static Leave(TInt aErrorCode);
...
};
The TRAP() and TRAPD() macros are also defined in e32std.h; edited slightly, they look
like this:
#define TRAP(_r,_s) { \
TTrap __t; \
if(__t.Trap(_r) == 0) \
{ \
_s; \
TTrap::UnTrap(); \
} \
}
#define TRAPD(_r,_s) TInt _r; \
{ \