Re: [Boost-users] [exception] nested exceptions: lost information?

Emil Dotchevski schrieb:

By design, boost::copy_exception slices. Its intended use is to obtain an exception_ptr without throwing an exception, as in:

exception_ptr p=copy_exception(foo());

(the result being that rethrow_exception(p) will throw foo.)

To copy the current exception in a catch, use

catch(...) { exception_ptr p=current_exception(); }

Emil Dotchevski Reverge Studios, Inc. http://www.revergestudios.com/reblog/index.php?n=ReCode

On Wed, Sep 23, 2009 at 8:13 AM, Pascal Z. wrote:

...

Hello

I'm trying to nest exceptions using boost.Exception, but it seems like some information (in this case the message returned via what() ) is lost on the way.

#include <iostream> #include

typedef boost::error_info nested_exception;

struct file_open_error : public boost::exception, public std::exception {};

int open_file(const std::string& filename) { try { // ... throw std::runtime_error("Some internal error."); } catch(const std::exception& error) { throw file_open_error() << nested_exception(boost::copy_exception(error)); } }

int main(int argc, char* argv[]) { try { int file = open_file("foo.txt"); file++;

} catch(const boost::exception& error) { try {

boost::rethrow_exception(*boost::get_error_info(error)); } catch(const std::exception& nested) { std::cout << "the nested error is: " << nested.what() << std::endl; } } return 0; }

I except the output to be "the nested error is: Some internal error." but it outputs "the nested error is: std::exception". What can I do to make it work?

Greetings Pascal

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Thanks, it's working now. =)