bpo-30853: IDLE: Convert font and general vars to use VarTrace (#2914)

Instance tracers manages pairs consisting of a tk variable and a callback function. When tracing is turned on, setting the variable calls the function. Test coverage for the new class is 100%.

Author: csabella

Lib/idlelib/configdialog.py

@@ -30,6 +30,7 @@
 
 changes = ConfigChanges()
 
+
 class ConfigDialog(Toplevel):
  """Config dialog for IDLE.
  """
@@ -75,13 +76,15 @@ def __init__(self, parent, title='', _htest=False, _utest=False):
  # self.bind('<Alt-a>', self.Apply) #apply changes, save
  # self.bind('<F1>', self.Help) #context help
  self.load_configs()
- self.attach_var_callbacks() # Avoid callbacks during load_configs.
+ # Avoid callbacks during load_configs.
+ tracers.attach()
 
  if not _utest:
  self.grab_set()
  self.wm_deiconify()
  self.wait_window()
 
+
  def create_widgets(self):
  """Create and place widgets for tabbed dialog.
 
@@ -96,7 +99,6 @@ def create_widgets(self):
  create_page_extensions
  create_action_buttons
  load_configs: Load pages except for extensions.
- attach_var_callbacks
  remove_var_callbacks
  activate_config_changes: Tell editors to reload.
  """
@@ -131,37 +133,9 @@ def load_configs(self):
  self.load_general_cfg()
  # note: extension page handled separately
 
- def attach_var_callbacks(self):
- "Attach callbacks to variables that can be changed."
- self.font_size.trace_add('write', self.var_changed_font)
- self.font_name.trace_add('write', self.var_changed_font)
- self.font_bold.trace_add('write', self.var_changed_font)
- self.space_num.trace_add('write', self.var_changed_space_num)
- self.color.trace_add('write', self.var_changed_color)
- self.builtin_theme.trace_add('write', self.var_changed_builtin_theme)
- self.custom_theme.trace_add('write', self.var_changed_custom_theme)
- self.is_builtin_theme.trace_add('write', self.var_changed_is_builtin_theme)
- self.highlight_target.trace_add('write', self.var_changed_highlight_target)
- self.keybinding.trace_add('write', self.var_changed_keybinding)
- self.builtin_keys.trace_add('write', self.var_changed_builtin_keys)
- self.custom_keys.trace_add('write', self.var_changed_custom_keys)
- self.are_keys_builtin.trace_add('write', self.var_changed_are_keys_builtin)
- self.win_width.trace_add('write', self.var_changed_win_width)
- self.win_height.trace_add('write', self.var_changed_win_height)
- self.startup_edit.trace_add('write', self.var_changed_startup_edit)
- self.autosave.trace_add('write', self.var_changed_autosave)
-
  def remove_var_callbacks(self):
  "Remove callbacks to prevent memory leaks."
- for var in (
- self.font_size, self.font_name, self.font_bold,
- self.space_num, self.color, self.builtin_theme,
- self.custom_theme, self.is_builtin_theme, self.highlight_target,
- self.keybinding, self.builtin_keys, self.custom_keys,
- self.are_keys_builtin, self.win_width, self.win_height,
- self.startup_edit, self.autosave,):
- var.trace_remove('write', var.trace_info()[0][1])
-
+ tracers.detach()
 
  def create_action_buttons(self):
  """Return frame of action buttons for dialog.
@@ -273,7 +247,7 @@ def create_page_font_tab(self):
 
  Tabs: Enable users to change spaces entered for indent tabs.
  Changing indent_scale value with the mouse sets Var space_num,
- which invokes var_changed_space_num, which adds an entry to
+ which invokes the default callback to add an entry to
  changes. Load_tab_cfg initializes space_num to default.
 
  Widget Structure: (*) widgets bound to self
@@ -294,10 +268,10 @@ def create_page_font_tab(self):
  (*)indent_scale: Scale - space_num
  """
  parent = self.parent
- self.font_name = StringVar(parent)
- self.font_size = StringVar(parent)
- self.font_bold = BooleanVar(parent)
- self.space_num = IntVar(parent)
+ self.font_name = tracers.add(StringVar(parent), self.var_changed_font)
+ self.font_size = tracers.add(StringVar(parent), self.var_changed_font)
+ self.font_bold = tracers.add(BooleanVar(parent), self.var_changed_font)
+ self.space_num = tracers.add(IntVar(parent), ('main', 'Indent', 'num-spaces'))
 
  # Create widgets:
  # body and body section frames.
@@ -443,12 +417,6 @@ def load_tab_cfg(self):
  'main', 'Indent', 'num-spaces', default=4, type='int')
  self.space_num.set(space_num)
 
- def var_changed_space_num(self, *params):
- "Store change to indentation size."
- value = self.space_num.get()
- changes.add_option('main', 'Indent', 'num-spaces', value)
-
-
  def create_page_highlight(self):
  """Return frame of widgets for Highlighting tab.
 
@@ -518,12 +486,17 @@ def create_page_highlight(self):
  'Shell Stderr Text': ('stderr', '13'),
  }
  parent = self.parent
- self.builtin_theme = StringVar(parent)
- self.custom_theme = StringVar(parent)
+ self.builtin_theme = tracers.add(
+ StringVar(parent), self.var_changed_builtin_theme)
+ self.custom_theme = tracers.add(
+ StringVar(parent), self.var_changed_custom_theme)
  self.fg_bg_toggle = BooleanVar(parent)
- self.color = StringVar(parent)
- self.is_builtin_theme = BooleanVar(parent)
- self.highlight_target = StringVar(parent)
+ self.color = tracers.add(
+ StringVar(parent), self.var_changed_color)
+ self.is_builtin_theme = tracers.add(
+ BooleanVar(parent), self.var_changed_is_builtin_theme)
+ self.highlight_target = tracers.add(
+ StringVar(parent), self.var_changed_highlight_target)
 
  ##widget creation
  #body frame
@@ -1062,10 +1035,14 @@ def create_page_keys(self):
  button_save_custom_keys: Button
  """
  parent = self.parent
- self.builtin_keys = StringVar(parent)
- self.custom_keys = StringVar(parent)
- self.are_keys_builtin = BooleanVar(parent)
- self.keybinding = StringVar(parent)
+ self.builtin_keys = tracers.add(
+ StringVar(parent), self.var_changed_builtin_keys)
+ self.custom_keys = tracers.add(
+ StringVar(parent), self.var_changed_custom_keys)
+ self.are_keys_builtin = tracers.add(
+ BooleanVar(parent), self.var_changed_are_keys_builtin)
+ self.keybinding = tracers.add(
+ StringVar(parent), self.var_changed_keybinding)
 
  ##widget creation
  #body frame
@@ -1169,9 +1146,6 @@ def load_key_cfg(self):
  keyset_name = idleConf.CurrentKeys()
  self.load_keys_list(keyset_name)
 
-
-
-
  def var_changed_builtin_keys(self, *params):
  "Process selection of builtin key set."
  old_keys = (
@@ -1434,7 +1408,7 @@ def create_page_general(self):
  set var startup_edit. Radiobuttons save_ask_on and save_auto_on
  set var autosave. Entry boxes win_width_int and win_height_int
  set var win_width and win_height. Setting var_name invokes the
- var_changed_var_name callback that adds option to changes.
+ default callback that adds option to changes.
 
  Helplist: load_general_cfg loads list user_helplist with
  name, position pairs and copies names to listbox helplist.
@@ -1470,10 +1444,14 @@ def create_page_general(self):
  scroll_helplist: Scrollbar
  """
  parent = self.parent
- self.startup_edit = IntVar(parent)
- self.autosave = IntVar(parent)
- self.win_width = StringVar(parent)
- self.win_height = StringVar(parent)
+ self.startup_edit = tracers.add(
+ IntVar(parent), ('main', 'General', 'editor-on-startup'))
+ self.autosave = tracers.add(
+ IntVar(parent), ('main', 'General', 'autosave'))
+ self.win_width = tracers.add(
+ StringVar(parent), ('main', 'EditorWindow', 'width'))
+ self.win_height = tracers.add(
+ StringVar(parent), ('main', 'EditorWindow', 'height'))
 
  # Create widgets:
  # body.
@@ -1873,9 +1851,9 @@ def add(self, var, callback):
 
  Args:
  var: Tk variable instance.
- callback: Function to be used as a callback or
- a tuple with IdleConf values for default
- callback.
+ callback: Either function name to be used as a callback
+ or a tuple with IdleConf config-type, section, and
+ option names used in the default callback.
 
  Return:
  Tk variable instance.
@@ -1908,6 +1886,8 @@ def detach(self):
  self.untraced.append((var, callback))
 
 
+tracers = VarTrace()
+
 help_common = '''\
 When you click either the Apply or Ok buttons, settings in this
 dialog that are different from IDLE's default are saved in

Misc/NEWS.d/next/IDLE/2017-07-27-10-01-14.bpo-30853.enPvvc.rst

@@ -0,0 +1,5 @@
+IDLE -- Factor a VarTrace class out of ConfigDialog.
+
+Instance tracers manages pairs consisting of a tk variable and a
+callback function. When tracing is turned on, setting the variable
+calls the function. Test coverage for the new class is 100%.