procutil: explain better why line buffering is not possible
The sentence “On Python 3, buffered binary streams can't be set line-buffered.”
was imprecise, as all streams are just Python classes and we can implement our
own (which we did).
--- a/mercurial/utils/procutil.py Tue Jul 07 12:13:40 2020 +0200
+++ b/mercurial/utils/procutil.py Fri Jul 10 09:55:38 2020 +0200
@@ -99,9 +99,10 @@
# buffering.
if isatty(stdout):
if pycompat.ispy3 or pycompat.iswindows:
- # On Python 3, buffered binary streams can't be set line-buffered.
- # On Python 2, Windows doesn't support line buffering.
- # Therefore we have a wrapper that implements line buffering.
+ # Python 3 implements its own I/O streams.
+ # The standard library doesn't offer line-buffered binary streams.
+ # Python 2 uses the I/O streams provided by the C library.
+ # The Windows C runtime library doesn't support line buffering.
stdout = make_line_buffered(stdout)
else:
stdout = os.fdopen(stdout.fileno(), 'wb', 1)