Argparse print_help() and print_usage() do not color based on their file argument

[bulletmark]

Bug report

Bug description:

Currently (in Python 3.14), both argparse.print_help() and argparse.print_usage() merely check whether stdout is eligible for coloring but both take a file argument and both should be checking against that instead of stdout. E.g. my app's stdout is attached to a file but I need sometimes to write my help/usage to the screen (e.g. via /dev/tty) and presently this is output without color although it can be (and looks much better!).

I made a very trivial patch to 3.14 argparse.py to fix this and was going to submit that as PR but there have been many recent changes to the same code so I decided just to raise this issue and attach my patch here.

No user or public facing API is changed so no documentation requires update.

Note also that no AI was used here, all implemented and tested by hand.

CPython versions tested on:

3.14

Operating systems tested on:

Arch Linux - up to date.

[bulletmark]

The trivial patch against Python 3.14 to fix this:

diff --git a/argparse.py b/argparse.py
index a106a71..721e658 100644
--- a/worktree_aid/argparse.py
+++ b/worktree_aid/argparse.py
@@ -196,10 +196,10 @@ class HelpFormatter(object):
         self._whitespace_matcher = _re.compile(r'\s+', _re.ASCII)
         self._long_break_matcher = _re.compile(r'\n\n\n+')
 
-    def _set_color(self, color):
+    def _set_color(self, color, file=None):
         from _colorize import can_colorize, decolor, get_theme
 
-        if color and can_colorize():
+        if color and can_colorize(file=file):
             self._theme = get_theme(force_color=True).argparse
             self._decolor = decolor
         else:
@@ -2699,14 +2699,17 @@ class ArgumentParser(_AttributeHolder, _ActionsContainer):
     # Help-formatting methods
     # =======================
 
-    def format_usage(self):
-        formatter = self._get_formatter()
+    def _format_usage(self, file=None):
+        formatter = self._get_formatter(file)
         formatter.add_usage(self.usage, self._actions,
                             self._mutually_exclusive_groups)
         return formatter.format_help()
 
-    def format_help(self):
-        formatter = self._get_formatter()
+    def format_usage(self):
+        return self._format_usage()
+
+    def _format_help(self, file=None):
+        formatter = self._get_formatter(file)
 
         # usage
         formatter.add_usage(self.usage, self._actions,
@@ -2728,9 +2731,12 @@ class ArgumentParser(_AttributeHolder, _ActionsContainer):
         # determine help from format above
         return formatter.format_help()
 
-    def _get_formatter(self):
+    def format_help(self):
+        return self._format_help()
+
+    def _get_formatter(self, file=None):
         formatter = self.formatter_class(prog=self.prog)
-        formatter._set_color(self.color)
+        formatter._set_color(self.color, file)
         return formatter
 
     def _get_validation_formatter(self):
@@ -2747,12 +2753,12 @@ class ArgumentParser(_AttributeHolder, _ActionsContainer):
     def print_usage(self, file=None):
         if file is None:
             file = _sys.stdout
-        self._print_message(self.format_usage(), file)
+        self._print_message(self._format_usage(file), file)
 
     def print_help(self, file=None):
         if file is None:
             file = _sys.stdout
-        self._print_message(self.format_help(), file)
+        self._print_message(self._format_help(file), file)
 
     def _print_message(self, message, file=None):
         if message:

[hugovk]

@bulletmark Please can you include a minimal, reproducible code example?

[aisk]

And can you also try this issue on 3.15 or newer version, because I see #139946 may have some related changes.

[bulletmark]

Just tried 3.15.0rc1 and yes, it fixes this bug, for both print_help() and print_usage().

Do you still want me to create a minimal example, e.g. to back-fit my or other patch to fix 3.14?

[aisk]

Thank you for ensure this! So this is already fixed on 3.15 (and main branch) by #140495 with original issue #139946, using a different approach compare to your patch.

That PR was not backported to 3.14 because it may break subclasses, see the discussion there.

Since this bug only means color is missing, and nothing is broken, I think fixing 3.14 with a different approach than main branch is not worth it, it adds maintenance cost and makes future backports harder. Leaving 3.14 as it is seems better to me.

[picnixz]

Closing as fixed in 3.15.0+ and won't fix for 3.14.

[bulletmark]

If anybody else comes along, I added the following to my application startup to address this issue:

    if sys.version_info[:2] == (3, 14) and 'FORCE_COLOR' not in os.environ:
        os.environ['FORCE_COLOR'] = '1'