Defined in header <exception> | ||
---|---|---|
template< class E > void rethrow_if_nested( const E& e ); | (since C++11) |
If E
is not a polymorphic class type, or if std::nested_exception
is an inaccessible or ambiguous base class of E
, there is no effect.
Otherwise, performs.
e | - | the exception object to rethrow |
(none).
Unlike many related functions, this function is not intended to be called with a std::exception_ptr
but rather an actual exception reference.
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& 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:
(C++11) | a mixin type to capture and store current exceptions (class) |
(C++11) | throws its argument with std::nested_exception mixed in (function template) |
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