rwexcept.cpp

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#include <exception>      // for exception
#include <iostream>       // for cerr
#include <vector>         // for vector
#include <cstdlib>        // for exit()
 
#include <rw/_error.h>    // for __rw_throw_proc, _RWSTD_ERROR_BAD_CAST
 
#include <examples.h>
 
 
// function called from within the library to throw an exception
void exception_handler (int id, char *what)
{
    std::cerr << "exception #" <<  id << ": " << what << '\n';
 
    // free what buffer
    if (what)
        __rw::__rw_free_what_buf (what);
 
    // a real program would call abort() here to prevent the potentially
    // dangerous destruction of objects with static storage duration
    // abort ();
 
    // introduce exit into the current scope if it's declared in namespace
    // std (as it should be) to allow referring to the function without
    // qualification when <cstdlib> incorrectly declares it at file scope
    using namespace std;
 
    // successfully exit the process
    exit (0);
 
    // return at your own risk
}
 
 
// prevent the allocation of more than 4 elements
struct Allocator: std::allocator<int>
{
    size_type max_size () const {
        return 4;
    }
};
 
 
int main ()
{
    typedef std::vector<int, Allocator> Vector;
 
    Vector v;
 
    for (Vector::size_type n = 0; n != 2 * v.max_size (); ++n) {
        try {
            // try to reserve storage for `n' values
            v.reserve (n);
        }
        catch (std::exception &e) {
            std::cerr << "caught an exception:" << e.what () << '\n';
 
            // after the first exception has been caught
            // replace the default throw procedure used
            // by the library with a user-defined exception
            // function and continue to iterate
            __rw::__rw_throw_proc = exception_handler;
        }
    }
 
    // should not reach
    std::cerr << "unexpected return from main\n";
 
    return 1;
}