Boost Exception

Diagnostic Information

Boost Exception provides a namespace-scope function diagnostic_information which takes a boost::exception. The returned string contains:

the string representation of all data objects added to the boost::exception through operator<<;
the output from std::exception::what;
additional platform-specific diagnostic information.

The returned string is not presentable as a friendly user message, but because it is generated automatically, it is useful for debugging or logging purposes. Here is an example:

#include <boost/exception/all.hpp>
#include <iostream>

void f(); //throws unknown types that derive from boost::exception.

void
g()
    {
    try
        {
        f();
        }
    catch(
    boost::exception & e )
        {
        std::cerr << diagnostic_information(e);
        }
    }

Example:

this is a possible output from the diagnostic_information function, as used in libs/exception/example/example_io.cpp:

example_io.cpp(70): Throw in function class boost::shared_ptr<struct _iobuf> __cdecl my_fopen(const char *,const char *)
Dynamic exception type: class boost::exception_detail::clone_impl<struct fopen_error>
std::exception::what: example_io error
[struct boost::errinfo_api_function_ *] = fopen
[struct boost::errinfo_errno_ *] = 2, "No such file or directory"
[struct boost::errinfo_file_name_ *] = tmp1.txt
[struct boost::errinfo_file_open_mode_ *] = rb