[3.6] bpo-30853: IDLE: Factor a VarTrace class from configdialog.ConfigDialog. (GH-2872) (#2903)
The new class manages pairs of tk Variables and trace callbacks.
It is completely covered by new tests.
(cherry picked from commit 45bf723)
diff --git a/Lib/idlelib/configdialog.py b/Lib/idlelib/configdialog.py
index 1832e15..f98af46 100644
--- a/Lib/idlelib/configdialog.py
+++ b/Lib/idlelib/configdialog.py
@@ -1846,6 +1846,61 @@
self.ext_userCfg.Save()
+class VarTrace:
+ """Maintain Tk variables trace state."""
+
+ def __init__(self):
+ """Store Tk variables and callbacks.
+
+ untraced: List of tuples (var, callback)
+ that do not have the callback attached
+ to the Tk var.
+ traced: List of tuples (var, callback) where
+ that callback has been attached to the var.
+ """
+ self.untraced = []
+ self.traced = []
+
+ def add(self, var, callback):
+ """Add (var, callback) tuple to untraced list.
+
+ Args:
+ var: Tk variable instance.
+ callback: Function to be used as a callback or
+ a tuple with IdleConf values for default
+ callback.
+
+ Return:
+ Tk variable instance.
+ """
+ if isinstance(callback, tuple):
+ callback = self.make_callback(var, callback)
+ self.untraced.append((var, callback))
+ return var
+
+ @staticmethod
+ def make_callback(var, config):
+ "Return default callback function to add values to changes instance."
+ def default_callback(*params):
+ "Add config values to changes instance."
+ changes.add_option(*config, var.get())
+ return default_callback
+
+ def attach(self):
+ "Attach callback to all vars that are not traced."
+ while self.untraced:
+ var, callback = self.untraced.pop()
+ var.trace_add('write', callback)
+ self.traced.append((var, callback))
+
+ def detach(self):
+ "Remove callback from traced vars."
+ while self.traced:
+ var, callback = self.traced.pop()
+ var.trace_remove('write', var.trace_info()[0][1])
+ self.untraced.append((var, callback))
+
+
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