Martin Slater wrote:
When you use a stream, rather than a streambuf, exceptions are caught automatically and translated into stream state, unless you set the exception mask to request that exceptions be propagated. (See http://www.boost.org/libs/iostreams/doc/index.html?path=3.10)
The only time you have to be prepared to handle exceptions is when you are using a raw stream buffer.
Just to be sure, were using an old version with boost 1.32 where stream == source.
I don't think stream was ever equivalent to source.
What I'm finding is that in the constructor where it is passed a file to open it gets passed through to our code and the file doesn't exist
Are you talking about errors which occur in Source constructors, e.g. (using 1.32 naming) stream_facade< random_source > in; in.open( random_source(4320243) ); // What happens if // constructor fails? ?
the only way we have of reporting an error is through an exception but this doesn't get caught and translated by the stream_facade but propogated straight out to our code.
stream_facade doesn't catch and rethrow exceptions which occur during open(). You can change this by modifying stream_facade::open_impl so that it looks something like the following (I'm not sure exactly what the code in your version looks like): void open_impl(const Device& dev BOOST_IOSTREAMS_PUSH_PARAMS()) { this->clear(); try { this->member.open(dev BOOST_IOSTREAMS_PUSH_ARGS()); } catch(...) { this->clear(std::ios_base::badbit); if (this->exceptions() & std::ios_base::badbit) throw; } } Alternatively, you could give your Source a member function 'good' returning a bool, and do stream_facade< random_source > in( random_source(888) ); if (in->good()) { ... } Lastly, you could set a flag in the constructor and have subsequent read or write requests fail is the construction was unsuccessful. I'll consider adding the above code to open_impl() for 1.34 (or maybe 1.33.1, since it seems like a harmless change, and improves usability). Thanks for bringing this to my attention.
Has this behaviour changed in 1.33 or is there something i'm missing?
thanks
Martin
Jonathan