Add a new option active_tab_title_template to specify a different template for active tab titles

Fixes #2198

docs/changelog.rst

@@ -19,6 +19,9 @@ To update |kitty|, :doc:`follow the instructions <binary>`.
 - Add a new option :opt:`tab_bar_background` to specify a different color
   for the tab bar (:iss:`2198`)
 
+- Add a new option :opt:`active_tab_title_template` to specify a different
+  template for active tab titles (:iss:`2198`)
+
 0.15.0 [2019-11-27]
 --------------------
 

kitty/config_data.py

@@ -716,12 +716,20 @@ def tab_fade(x):
 o('tab_separator', '"{}"'.format(default_tab_separator), option_type=tab_separator, long_text=_('''
 The separator between tabs in the tab bar when using :code:`separator` as the :opt:`tab_bar_style`.'''))
 
+
+def active_tab_title_template(x):
+    return None if x == 'none' else x
+
+
 o('tab_title_template', '{title}', long_text=_('''
 A template to render the tab title. The default just renders
 the title. If you wish to include the tab-index as well,
 use something like: :code:`{index}: {title}`. Useful
 if you have shortcuts mapped for :code:`goto_tab N`.
 '''))
+o('active_tab_title_template', 'none', option_type=active_tab_title_template, long_text=_('''
+Template to use for active tabs, if not specified falls back
+to :opt:`tab_title_template`.'''))
 
 o('active_tab_foreground', '#000', option_type=to_color, long_text=_('''
 Tab bar colors and styles'''))

kitty/tab_bar.py

@@ -18,25 +18,32 @@
 TabBarData = namedtuple('TabBarData', 'title is_active needs_attention')
 DrawData = namedtuple(
     'DrawData', 'leading_spaces sep trailing_spaces bell_on_tab'
-    ' bell_fg alpha active_fg active_bg inactive_fg inactive_bg default_bg title_template')
+    ' bell_fg alpha active_fg active_bg inactive_fg inactive_bg'
+    ' default_bg title_template active_title_template')
 
 
 def as_rgb(x):
     return (x << 8) | 2
 
 
+template_failures = set()
+
+
 def draw_title(draw_data, screen, tab, index):
     if tab.needs_attention and draw_data.bell_on_tab:
         fg = screen.cursor.fg
         screen.cursor.fg = draw_data.bell_fg
         screen.draw('🔔 ')
         screen.cursor.fg = fg
+    template = draw_data.title_template
+    if tab.is_active and draw_data.active_title_template is not None:
+        template = draw_data.active_title_template
     try:
-        title = draw_data.title_template.format(title=tab.title, index=index)
+        title = template.format(title=tab.title, index=index)
     except Exception as e:
-        if not hasattr(draw_title, 'template_failure_reported'):
-            draw_title.template_failure_reported = True
-            log_error('Invalid tab title template: "{}" with error: {}'.format(draw_data.title_template, e))
+        if template not in template_failures:
+            template_failures.add(template)
+            log_error('Invalid tab title template: "{}" with error: {}'.format(template, e))
         title = tab.title
     screen.draw(title)
 
@@ -144,7 +151,6 @@ class TabBar:
     def __init__(self, os_window_id, opts):
         self.os_window_id = os_window_id
         self.opts = opts
-        draw_title.template = opts.tab_title_template
         self.num_tabs = 1
         self.margin_width = pt_to_px(self.opts.tab_bar_margin_width, self.os_window_id)
         self.cell_width, cell_height = cell_size_for_window(self.os_window_id)
@@ -177,7 +183,8 @@ def __init__(self, os_window_id, opts):
             self.leading_spaces, self.sep, self.trailing_spaces, self.opts.bell_on_tab, self.bell_fg,
             self.opts.tab_fade, self.opts.active_tab_foreground, self.opts.active_tab_background,
             self.opts.inactive_tab_foreground, self.opts.inactive_tab_background,
-            self.opts.tab_bar_background or self.opts.background, self.opts.tab_title_template
+            self.opts.tab_bar_background or self.opts.background, self.opts.tab_title_template,
+            self.opts.active_tab_title_template
         )
         if self.opts.tab_bar_style == 'separator':
             self.draw_func = draw_tab_with_separator