[PATCH] RFC: ui.style only for tty, ui.ttystyle

[Yuya Nishihara]

# HG changeset patch
# User Yuya Nishihara <yuya at tcha.org>
# Date 1265873127 -32400
# Node ID 3a6e034ff3dd3308d55f7e8e791176a6b5d0a4fa
# Parent  b59fba37e5e6ffd45cabfbfd8f70f9554f3dbee5
RFC: ui.style only for tty, ui.ttystyle

`ui.style' is great for customizing `hg log' output.
But once ui.style set, some third-party tools, e.g. emacs vc or dvc,
don't work correctly because they depend on the default log style.

This introduces `ui.ttystyle' to change the style only for tty output.

This is also good for specifying colorized styles like:
http://hgtip.com/tips/advanced/2010-01-15-styling-mercurials-cli/

diff --git a/mercurial/cmdutil.py b/mercurial/cmdutil.py
--- a/mercurial/cmdutil.py
+++ b/mercurial/cmdutil.py
@@ -884,7 +884,8 @@ def show_changeset(ui, repo, opts, buffe
     1. option 'template'
     2. option 'style'
     3. [ui] setting 'logtemplate'
-    4. [ui] setting 'style'
+    4. [ui] setting 'ttystyle' if stdout is a tty
+    5. [ui] setting 'style'
     If all of these values are either the unset or the empty string,
     regular display via changeset_printer() is done.
     """
@@ -906,7 +907,11 @@ def show_changeset(ui, repo, opts, buffe
         if tmpl:
             tmpl = templater.parsestring(tmpl)
         else:
-            style = util.expandpath(ui.config('ui', 'style', ''))
+            # hgext.pager replaces sys.stdout by a pager process
+            if sys.__stdout__.isatty():
+                style = util.expandpath(ui.config('ui', 'ttystyle', ''))
+            if not style:
+                style = util.expandpath(ui.config('ui', 'style', ''))
 
     if not (tmpl or style):
         return changeset_printer(ui, repo, patch, opts, buffered)