std::throw_with_nested
From cppreference.com
| Defined in header <exception>
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| template< class T > [[noreturn]] void throw_with_nested( T&& t ); |
(since C++11) | |
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.
If std::remove_reference<T>::type is already derived from std::nested_exception, simply throws std::forward<T>(t).
Requires that std::remove_reference<T>::type is Template:concept
Contents |
Parameters
| t | - | the exception object to throw |
Return value
(none)
Example
Demonstrates construction and recursion through a nested exception object.
Run this code
#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 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
