std:: throw_with_nested

Si std:: decay < T > :: type es un tipo de clase no final y no unión que no es std::nested_exception ni derivado de std::nested_exception , lanza una excepción de un tipo no especificado que deriva públicamente tanto de std::nested_exception como de std:: decay < T > :: type , y construida a partir de std:: forward < T > ( t ) . El constructor por defecto de la clase base nested_exception llama a std::current_exception , capturando el objeto de excepción actualmente manejado, si existe, en un std::exception_ptr .

De lo contrario, lanza std:: forward < T > ( t ) .

Requiere que std:: decay < T > :: type sea CopyConstructible .

Parámetros

Notas

Ejemplo

#include <exception>
#include <fstream>
#include <iostream>
#include <stdexcept>
#include <string>
// prints the explanatory string of an exception. If the exception is nested,
// recurses to print the explanatory string of the exception it holds
void print_exception(const std::exception& e, int level =  0)
{
    std::cerr << std::string(level, ' ') << "exception: " << e.what() << '\n';
    try
    {
        std::rethrow_if_nested(e);
    }
    catch (const std::exception& nestedException)
    {
        print_exception(nestedException, level + 1);
    }
    catch (...) {}
}
// sample function that catches an exception and wraps it in a nested exception
void open_file(const std::string& s)
{
    try
    {
        std::ifstream file(s);
        file.exceptions(std::ios_base::failbit);
    }
    catch (...)
    {
        std::throw_with_nested(std::runtime_error("Couldn't open " + s));
    }
}
// sample function that catches an exception and wraps it in a nested exception
void run()
{
    try
    {
        open_file("nonexistent.file");
    }
    catch (...)
    {
        std::throw_with_nested(std::runtime_error("run() failed"));
    }
}
// runs the sample function above and prints the caught exception
int main()
{
    try
    {
        run();
    }
    catch (const std::exception& e)
    {
        print_exception(e);
    }
}

exception: run() failed
 exception: Couldn't open nonexistent.file
  exception: basic_ios::clear

Véase también