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std::throw_with_nested - cppreference.com

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Definido no cabeçalho `<exception>`

`template< class T > [[noreturn]] void throw_with_nested( T&& t );`		(desde C++11)

Gera uma exceção do tipo não especificado, que é derivado a partir de ambas std::nested_exception e de std::remove_reference<T>::type, e construído a partir de std::forward<T>(t). O construtor padrão do pai nested_exception chama std::current_exception, capturando o objeto de exceção atualmente tratado, se houver, em std::exception_ptr.

Original:

Throws an exception of unspecified type that is derived from both std::nested_exception and from std::remove_reference<T>::type, and constructed from std::forward<T>(t). The default constructor of the nested_exception parent calls std::current_exception, capturing the currently handled exception object, if any, in std::exception_ptr.

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Se já estiver std::remove_reference<T>::type derivado std::nested_exception, simplesmente lança std::forward<T>(t).

Original:

If std::remove_reference<T>::type is already derived from std::nested_exception, simply throws std::forward<T>(t).

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Requer que std::remove_reference<T>::type é CopyConstructible

Original:

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Parâmetros

t

-

o objeto de exceção para jogar

Original:

the exception object to throw

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Valor de retorno

(Nenhum)

Original:

(none)

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Exemplo

Demonstra construção e recursividade através de um objeto de exceção aninhada

Original:

Demonstrates construction and recursion through a nested exception object

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#include <iostream>
#include <stdexcept>
#include <exception>
#include <string>
#include <fstream>

// prints the explanatory string of an exception. If the exception is nested,
// recurses to print the explanatory 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& e) {
        print_exception(e, 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);
    }
}

Saída:

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

Veja também


	um tipo mixin para capturar e armazenar as exceções atuais Original: a mixin type to capture and store current exceptions The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (classe) [edit]

	lança a exceção de um std::nested_exception Original: throws the exception from a std::nested_exception The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (modelo de função) [edit]