I see this is an old question but I think that the approach of printing the line in the exception macro is fundamentally flawed and I think I have a better alternative. I assume that the macro is used similar to the following code:
try {
/// code
throw;
}
catch (...) { __EXCEPTION(aMessage); }
With this approach the macro prints the location where the exception was catch'ed
. But for troubleshooting and debugging the location where it was throw'n
is usually more useful.
To get that information, we can attach the __FILE__
and __LINE__
macros to the exception. However, we still can't get completely rid of macros, but we get at least the exact throw location:
#include <iostream>
#include <exception>
#include <string>
#define MY_THROW(msg) throw my_error(__FILE__, __LINE__, msg)
struct my_error : std::exception
{
my_error(const std::string & f, int l, const std::string & m)
: file(f)
, line(l)
, message(m)
{}
std::string file;
int line;
std::string message;
char const * what() const throw() { return message.c_str(); }
};
void my_exceptionhandler()
{
try {
throw; // re-throw the exception and capture the correct type
}
catch (my_error & e)
{
std::cout << "Exception: " << e.what() << " in line: " << e.line << std::endl;
}
}
int main()
{
try {
MY_THROW("error1");
} catch(...) { my_exceptionhandler(); }
}
There is one additional improvement possible if we are willing to use boost::exception
: We can get rid of macro definitons at least in our own code. The whole program gets shorter and the locations of code execution and error handling can be nicely separated:
#include <iostream>
#include <boost/exception/all.hpp>
typedef boost::error_info<struct tag_error_msg, std::string> error_message;
struct error : virtual std::exception, virtual boost::exception { };
struct my_error: virtual error { };
void my_exceptionhandler()
{
using boost::get_error_info;
try {
throw;
}
catch(boost::exception & e)
{
char const * const * file = get_error_info<boost::throw_file>(e);
int const * line = get_error_info<boost::throw_line>(e);
char const * const * throw_func = get_error_info<boost::throw_function>(e);
std::cout << diagnostic_information(e, false)
<< " in File: " << *file << "(" << *line << ")"
" in Function: " << *throw_func;
}
}
int main()
{
try {
BOOST_THROW_EXCEPTION(my_error() << error_message("Test error"));
} catch(...) { my_exceptionhandler(); }
}