Glenn wrote:
> So if flush checks that bit, maybe TextIOWriter could just call buffer.flush, and it would be fast if clean and slow if dirty?

Yes. I'll benchmark how much overhead is added by the calls to flush; there's no point in breaking the abstraction boundary of BufferedWriter if it doesn't give a significant performance benefit. (I suspect that it might not, because Windows is very slow at scrolling a console, which might make the cost of flushing insignificant in comparison.)