std::rethrow_if_nested - cppreference.com

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Elemento definito nell'header `<exception>`

`template< class E > void rethrow_if_nested( const E& e );`		(dal C++11)

Se E è un tipo che è inequivocabilmente derivato da std::nested_exception, estratti e genera l'eccezione nidificata come se chiamando dynamic_cast<const std::nested_exception&>(e).rethrow_nested(). In caso contrario, non fa nulla.

Original:

If E is a type that is unambiguously derived from std::nested_exception, extracts and throws the nested exception as if by calling dynamic_cast<const std::nested_exception&>(e).rethrow_nested(). Otherwise, does nothing.

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Parametri

l'oggetto eccezione di ripetere la generazione

Original:

the exception object to rethrow

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Valore di ritorno

(Nessuno)

Original:

(none)

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Esempio

[edit]

Dimostra costruzione e ricorsione attraverso un oggetto eccezione nidificata

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);
    }
}

Output:

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

Vedi anche


	un tipo mixin per acquisire e memorizzare le eccezioni attuali 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) [modifica]

	lancia la sua tesi con std::nested_exception misto trovi Original: throws its argument with std::nested_exception mixed in The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (funzione di modello) [modifica]