thanks I get it, btw, I am using version 1.34.0 Andrew Holden wrote:

Af001 wrote:

...

Why can't I catch this exception in boost::thread?

#include <boost/thread/thread.hpp> #include <iostream> #include <exception>

void helloworld() { std::cout << "Hello World!" << std::endl; throw(std::string("err")); }

int main() { try { boost::thread thrd(&helloworld); thrd.join(); } catch(...) { std::cout<<"err"; } }

This is a limitation of exceptions in a multi-threaded environment. Exceptions must be caught in the same thread from which they are thrown. In your program, you created a new thread for helloworld(). Therefore, any exceptions thrown by helloworld will cause a runtime error, unless helloworld itself catches them. You should be able to work around this my storing the exception in a global variable or something. Perhaps:

#include <boost/thread/thread.hpp> #include <iostream> #include <exception>

volatile bool threaderror = false; std::string error;

void helloworld() { try { std::cout << "Hello World!" << std::endl; throw(std::string("err")); } catch (std::string &err) { threaderror = true; error = err; } }

int main() { try { boost::thread thrd(&helloworld); thrd.join(); if (threaderror) { throw error; } } catch(...) { std::cout<<"err"; } }

Notice how, in this version, helloworld() catches the exception itself and stores it in a global variable. Main() then checks the variable and throws a copy of the original exception.

Does anyone have any ideas for a cleaner version of this? It looks like boost.thread allows a functor for the initial function, so maybe you could convert helloworld() to a functor and declare those global variables I added as member variables, along with a member function to rethrow any exceptions caught.

Perhaps someone could create a generic version of this? It could maybe take a MPL list of exception types that it should marshall across threads. Is there a way to catch *any* exception in the thread and store it for a later rethrow? _______________________________________________ Boost-users mailing list Boost-users@lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users

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