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std::nested_exception(3) | C++ Standard Libary | std::nested_exception(3) |
NAME¶
std::nested_exception - std::nested_exception
Synopsis¶
Defined in header <exception>
class nested_exception; (since C++11)
std::nested_exception is a polymorphic mixin class which can capture and
store the
current exception, making it possible to nest exceptions of arbitrary types
within
each other.
Member functions¶
constructor constructs a nested_exception
(public member function)
destructor destructs a nested exception
[virtual] (virtual public member function)
operator= replaces the contents of a nested_exception
(public member function)
rethrow_nested throws the stored exception
(public member function)
nested_ptr obtains a pointer to the stored exception
(public member function)
Non-member functions¶
throw_with_nested throws its argument with std::nested_exception
mixed in
(C++11) (function template)
rethrow_if_nested throws the exception from a std::nested_exception
(C++11) (function template)
Example¶
Demonstrates construction and recursion through a nested exception object.
// Run this code
#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& 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);
}
}
Possible output:¶
exception: run() failed
exception: Couldn't open nonexistent.file
exception: basic_ios::clear
See also¶
exception_ptr shared pointer type for handling exception objects
(C++11) (typedef)
throw_with_nested throws its argument with std::nested_exception mixed in
(C++11) (function template)
rethrow_if_nested throws the exception from a std::nested_exception
(C++11) (function template)
2022.07.31 | http://cppreference.com |