id	summary	reporter	owner	description	type	status	milestone	component	version	severity	resolution	keywords	cc
2998	Make file_sink flushable	Andrew Schweitzer <a.schweitzer.grps@…>	Jonathan Turkanis	"file_sink is hard to use as a debug log, since it does not flush. 

For example, when used when pushed into a filtering_ostream with cout, if flush is not called, characters don't appear on console or in file in a timely fashion. If flush is called, the characters on the console appear but not those in the file, because file_sink does not implement Flushable concept, and doesn't flush. 

This code:
    filtering_ostream fo;

    file_sink fsink(""out.txt"");
    tee_filter<file_sink> tee_fsink(fsink);
    fo.push(tee_fsink);
    
    fo.push(cout);

    fo << ""some text"";
    fo.flush();

is very useful for arbitrary chains of debug logs, but not currently usable. 

The same issue applies to file, file_descriptor, and file_descriptor_sink. 

If there is some reason these classes should not be modified to made flushable, then it seems easy to make flushable_* versions. Example of this attached, which was copied from file.hpp. 

I also tried to add flushable_file_descriptor, by privately inheriting from file_descriptor, and adding a flush call which calls ::FlushFileBuffers on handle()... but so far that doesn't seem to work, so not attaching.

Discussion at
http://groups.google.com/group/boost-list/browse_thread/thread/4c07e7c255e8143a/b9003b1b83c5a4db?lnk=raot&pli=1
"	Feature Requests	closed	Boost 1.39.0	iostreams	Boost 1.38.0	Not Applicable	fixed