Error Handling - Cryptography in C and C++ - page 360

class LINT_Init : public LINT_Error // function argument illegal or uninitialized
{ ... };
class LINT_Nullptr : public LINT_Error // null pointer passed as argument
{ ... };
class LINT_OFL : public LINT_Error // overflow in function
{ ... };
class LINT_UFL : public LINT_Error // underflow in function
{ ... };
With this we are in a position, on the one hand, to catch LINT errors without
distinguishing specifically which error has occurred by inserting a catch block
catch (LINT_Error const &err) // notice: LINT_Error is abstract
{
// ...
err.debug_print();
// ...
}
after a try block, while on the other hand we can carry on a goal-directed search
for an individual error by specifying the appropriate error class as argument in
the catch instruction.
One should note that as an abstract base class LINT_Error is not instantiatable
as an object, for which reason the argument err can be passed only by reference
and not by value. Although all the LINT functions have been equipped with the
panic() instruction for error handling, the use of exceptions does not mean
that we must alter all the functions. Rather, we integrate the appropriate throw
instructions into the panic() routine, where they are called in conjunction with
the error that has been reported. Control is then transferred to the catch block,
which belongs to the try block of the calling function. The following code segment
of the function panic() clarifies the modus operandi:
void LINT::panic (LINT_ERRORS error, const char* func,
int arg, int line, const char* file)
{
if (LINT_User_Error_Handler)
{
LINT_User_Error_Handler (error, func, arg, line, file);
}