std::nested_exception - cppreference.com (original) (raw)

| | | | | ------------------------ | | ------------- | | 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.

[edit] Member functions

| | constructs a nested_exception (public member function) | | ------------------------------------------------------------------------ | | | destructs a nested exception (virtual public member function) | | | 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) |

[edit] Non-member functions

[edit] Notes

[edit] Example

Demonstrates construction and recursion through a nested exception object.

#include #include #include #include #include   // prints the explanatory string of an exception. If the exception is nested, // recurses to print the explanatory string 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

[edit] See also