Support std::exception_ptr in boost::promise

[ikispal@…]

Please add something like this to boost::promise:

void set_exception(std::exception_ptr e);

if std::exception_ptr is available.

I want to use boost futures, but don't want to wrap all of my throws in enable_current_exception(). See also: ​http://stackoverflow.com/questions/22010388/converting-stdexception-ptr-to-boostexception-ptr

[viboes]

I don't think this is possible in an efficient way. I would prefer the user do the conversion using a specific function. Maybe you should ask for this function to Boost.Exception library author.

[Matt Calabrese]

This is a fairly annoying problem for me as well, especially when writing code where you don't have control over the exception that's thrown -- all you want to do is intercept the exception by calling std::current_exception and set the promise. I need to use boost::futures because of facilities like wait_for_any, but the fact that it implies no longer being able to capture arbitrary exceptions is a fairly annoying problem. What exactly is the issue right now that prevents adding a std::exception_ptr overload when available? It seems like in the case that std::exception_ptr is available, boost::future/promise could deal with std::exception_ptr internally instead of boost::exception_ptr, correct? Both overloads could be provided (one for std::exception_ptr and one for boost::exception_ptr) since converting boost::exception_ptr to std::exception_ptr should be a much simpler conversion than the other way around and can be done inside the implementation of boost::promise. Perhaps I'm missing some subtleties, though?

[viboes]

Maybe you are right and converting from boost::exception_ptr to std::exception_ptr could be more efficient.

Ok, I will give it a try. I will request Emil a function to do the conversion, and apply it internally. I could also do the conversion using the external interfaces waiting for an efficient version.

[Matt Calabrese]

Replying to viboes:

Maybe you are right and converting from boost::exception_ptr to std::exception_ptr could be more efficient.

Ok, I will give it a try. I will request Emil a function to do the conversion, and apply it internally. I could also do the conversion using the external interfaces waiting for an efficient version.

Awesome, and thanks for such a quick reply to this!

[viboes]

Created #9769. Emil suggest to make boost::exception_ptr a typedef of std::exception_ptr when available.

[viboes]

I decided to don't fix this issue. #9769 should fix it.

[RelicOfTesla@…]

MSC_VER=1600,BOOST_VER=106000 invalid catch

void foo_lang_test()
{
	printf("MSC_VER=%d,BOOST_VER=%d\n", _MSC_VER , BOOST_VERSION );
	boost::promise<void> pp;
	try
	{
		throw std::runtime_error("aa");
	}
	catch(...)
	{
		pp.set_exception(std::current_exception());
	}
	try
	{
		pp.get_future().get();
	}
	catch(std::exception& e)
	{
		printf("catch %s\n", e.what());
	}
	catch(...)
	{
		printf("invalid catch\n");
	}
}