Re: [boost] [futures] boost::futures

From: Peter Dimov (pdimov_at_[hidden])
Date: 2007-03-12 15:32:00

Hess, Frank wrote:

> Splitting promise from future seems like a good idea, it should make
> the future class in libpoet a little less confusing.  One thing your
> code reminded me of is forwarding exceptions to the future, something
> I put 
> off then completely forgot about in libpoet.  Since I'm trying to
> provide an active function object that wraps an ordinary passive
> function, for the general case I would need to call something like
> your promise::fail() from a catch block that catches exceptions
> thrown by the passive function.  Unfortunately, that would require
> something like a templated catch.  It seems the best I can do is
> provide special handling 
> for some particular type of exception, like a
> boost::shared_ptr<std::exception> and if the passive function throws
> anything else, it just gets forwarded to the future as something like
> a poet::unknown_exception.

This won't be a problem in the next C++ if N2179 passes:

http://www.pdimov.com/cpp/N2179.html

My implementation provides a partial emulation of N2179:

http://www.pdimov.com/cpp/N2179/exception_ptr.hpp
http://www.pdimov.com/cpp/N2179/exception_ptr.cpp