| Defined in header <exception> | ||
|---|---|---|
class nested_exception; | (since C++11) |
std::nested_exceptions 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
| constructs a nested_exception (public member function) | |
| (destructor)
[virtual] | destructs a nested exception (virtual public member function) |
| operator=
| replaces the contents of a nested_exception (public member function) |
| throws the stored exception (public member function) | |
| obtains a pointer to the stored exception (public member function) |
Non-member functions
| (C++11) | throws its argument with std::nested_exception mixed in (function template) |
| (C++11) | throws the exception from a std::nested_exception (function template) |
Example
Demonstrates construction and recursion through a nested exception object.
#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
See also
| (C++11) | shared pointer type for handling exception objects (typedef) |
| (C++11) | throws its argument with std::nested_exception mixed in (function template) |
| (C++11) | throws the exception from a std::nested_exception (function template) |
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