On 9/8/16 4:53 AM, Somebody wrote:
If i write something like:writeln("what to do?"); switch(readln[0 .. $ - 1]) { //.. } writeln("bye"); ....that works just as it should at Windows, started from a command prompt. However, if I run it from GNU Emacs, I have to manually flush the output after each time I do it before taking input, or else the output does not show when it should. I wonder if write(...) and writeln(...) should automatically flush, to enhance portability? Of course, I may be issing missing something?
write and writeln depend on the behavior of FILE * for flushing, there is no specific flush.
Note that FILE * examines the file descriptor and if it is detected as an interactive descriptor, flush is done every newline. If not, then flush is only done when the buffer is full. This is standard behavior forever, and is done to avoid performance problems when piping the result of a command to a file, for instance (flushing is expensive).
Your emacs "console" is not marked by the OS as interactive (or however it's detected by FILE *, implementation defined), therefore flush does not happen on newlines.
If you want to force newline flushing, use http://dlang.org/phobos/std_stdio.html#.File.setvbuf with a mode parameter of _IOLBF.
-Steve
