Brian Braatz wrote:
On Behalf Of Jonathan Turkanis
The main point of the thread was to show how to write a sink with a built-in line-ending filter, so the user doesn't always have to add one explicitly.
Jonathan
[Brian Braatz Writes:] Yes. (sorry if I got off base)- the question relevant to boost \ iostreams was this-
You weren't off base -- I was summarizing the thread for Reid Sweatman, who asked what the thread was about.
Given a device which has different line termination than \n, how do you handle it in such a way that allows for that device to be able to interpret std::endl so it works as the user would expect. (and so the code you write using the sink makes sense to the user)
I happen to be using win32's outputdebugstring, but the same issue applies for "printing" to a windows edit control. The same issue might also apply to a daisy wheel printer. And, personally, I think boost should support daisy wheel printers (grin)....
I think this accurately describes the question -- now here's my question: are you satisfied with my answer? I had to correct my first answer, so let me restate it for clarity: 1. Implement the device as if it had no special line-endings requirements. If the final device will be called xxx, you might call this intermediate class xxx_impl. 2. Your final device should have a member yyy of type detail::chain<mode>. If you want to avoid details, a member of type filtering_stream<mode> or filtering_streambuf<mode> will do, but you have to wrap them so they are copy-constructible, perhaps using share_ptr< filtering_streambuf<mode> >. 3. In the constructor of your device, push a newline filter onto yyy's chain, then push an instance of xxx_impl. 4. implement the i/o functions (read, write, seek, ...) by delegation to yyy. For example: struct win32_debug_sink_impl : boost::iostreams::sink { ... }; struct win32_debug_sink : boost::iostreams::sink { win32_debug_sink() { using namespace boost::iostreams; chain_.push(newline_filter(newline::windows)); chain_.push(win32_debug_sink_impl); } void write(const char* s, std::streamsize n) { chain_.write(x, n); } boost::iostreams::detail::chain<output> chain_; }; Best, Jonathan