Got rid of lastValue/revert functionality. Changed the structure of...

Got rid of lastValue/revert functionality. Changed the structure of validation/notification so that programmatic notification is a bit safer, and should not result in infinitely recursive callbacks. Now, whenever a property value changes, the HasProperties instance is notified; it then forces validation/notification for all other properties. This is done because the validity of one property may be dependent upon the value of another. Also, added ability in build.py for buttons to be added to interface.

tkprop/build.py

@@ -12,8 +12,8 @@
 # accepts as parameters a tk object to be used as the parent (e.g. a
 # root or Frame object), a tkprop.HasProperties object, an optional
 # ViewItem object, which specifies how the interface is to be laid
-# out, and two optional dictionaries for passing in labels and
-# tooltips.
+# out, two optional dictionaries for passing in labels and tooltips,
+# and another optional dictionary for any buttons to be added.
 #
 # The view parameter allows the layout of the generated interface to
 # be customised.  Property widgets may be grouped together by embedding
@@ -592,7 +592,12 @@ def _prepareEvents(propObj, propGui):
         prop.addListener(propObj, lName, onChange)
  
 
-def buildGUI(parent, propObj, view=None, labels=None, tooltips=None):
+def buildGUI(parent,
+             propObj,
+             view=None,
+             labels=None,
+             tooltips=None,
+             buttons=None):
     """
     Builds a Tkinter/ttk interface which allows the properties of the
     given propObj object (a tkprop.HasProperties instance) to be edited.
@@ -609,6 +614,12 @@ def buildGUI(parent, propObj, view=None, labels=None, tooltips=None):
      - view:     ViewItem object, specifying the interface layout
      - labels:   Dict specifying labels
      - tooltips: Dict specifying tooltips
+     - buttons:  Dict specifying buttons to add to the interface.
+                 Keys are used as button labels, and values are
+                 callback functions which take two arguments - the
+                 Tkinter parent object, and the HasProperties
+                 object (parent and propObj). Make sure to use a
+                 collections.OrderedDict if order is important.
     """
 
     if view is None: view = _defaultView(propObj)
@@ -617,8 +628,30 @@ def buildGUI(parent, propObj, view=None, labels=None, tooltips=None):
     if tooltips is None: tooltips = {}
 
     propGui  = PropGUI()
-    view     = _prepareView(view, labels, tooltips)
-    topLevel = _create(parent, view, propObj, propGui)
+    view     = _prepareView(view, labels, tooltips) 
+
+    # If any buttons were specified, the properties
+    # interface is embedded in a higher level frame,
+    # along with the buttons
+    if len(buttons) > 0:
+        
+        topLevel  = ttk.Frame(parent)
+        propFrame = _create(topLevel, view, propObj, propGui)
+
+        topLevel.rowconfigure(   0, weight=1)
+        topLevel.columnconfigure(0, weight=1)
+        topLevel.columnconfigure(1, weight=1)
+
+        propFrame.grid(row=0, column=0, columnspan=2,
+                       sticky=tk.N+tk.S+tk.E+tk.W)
+
+        for i,(label,callback) in enumerate(buttons.items()):
+
+            button = ttk.Button(topLevel, text=label, command=callback)
+            button.grid(row=1, column=i, sticky=tk.N+tk.S+tk.E+tk.W)
+            
+    else:
+        topLevel = _create(parent, view, propObj, propGui)
 
     _prepareEvents(propObj, propGui)
 

tkprop/properties.py

@@ -163,7 +163,6 @@ class TkVarProxy(object):
         self.tkVarType       = tkVarType
         self.tkProp          = tkProp
         self.owner           = owner
-        self.lastValue       = value
         self.changeListeners = {}
         self.name            = name
         self.tkVar           = tkVarType(value=value, name=name)
@@ -173,11 +172,13 @@ class TkVarProxy(object):
     def addListener(self, name, callback):
         """
         Adds a listener for this variable. When the variable value
-        changes, the listener callback function is called. The
-        callback function must accept these arguments:
+        changes, the listener callback function is called. Listener
+        notification may also be programmatically triggered via the
+        PropertyBase.forceValidation method. The callback function
+        must accept these arguments:
 
-          value    - The new property value
-          valid    - Whether the new value is valid or invalid
+          value    - The property value
+          valid    - Whether the value is valid or invalid
           instance - The HasProperties instance
           tkProp   - The PropertyBase instance
           name     - The name of this TkVarProxy
@@ -202,25 +203,13 @@ class TkVarProxy(object):
         
         self.changeListeners[instance].pop(name, None)
 
-        
-    def _traceCb(self, *args):
+
+    def _getVarValue(self):
         """
-        Called whenever the Tkinter control variable value is changed.
-        The PropertyBase.validate() method is called on the parent
-        property of this TkVarProxy object. If this validate method
-        does not raise an error, the new value is stored as the last
-        known good value. If the validate method does raise an error,
-        the last known good value is not changed. The variable can
-        be reverted to its last known good value via the revert
-        method.
-        
-        After the PropertyBase.validate method is called, any registered
-        listeners are notified of the variable value change.
+        Returns the current value of the Tkinter control
+        variable being managed by this TkVarProxy object.
         """
 
-        valid     = True
-        listeners = self.changeListeners.items()
-
         # This is silly. Tkinter allows Boolean/Int/Double
         # variables to be set to invalid values (e.g. it
         # allows DoubleVars to be set to strings containing
@@ -229,12 +218,12 @@ class TkVarProxy(object):
         # the invalid value to a boolean/int/double. So here
         # we attempt to get the current value in the normal
         # way ...
-        try:    newValue = self.tkVar.get()
+        try:    value = self.tkVar.get()
 
         # and if that fails, we manually look up the value
         # via the current tk context, thus avoiding the
         # failing type cast. Ugly.
-        except: newValue = self.tkVar._tk.globalgetvar(self.name)
+        except: value = self.tkVar._tk.globalgetvar(self.name)
 
         # More silliness related to above silliness. All
         # variables in Tk, be they IntVars, BooleanVars, or
@@ -244,43 +233,55 @@ class TkVarProxy(object):
         # which is quite different. So I'm following the
         # convention that an empty string, for any of the 
         # variable types, is equivalent to None. 
-        if newValue == '':
-            newValue = None
-
-        # print a log message if the value has changed
-        if newValue != self.lastValue:
-            log.debug(
-                'Variable {} changed: {} (valid: {}, {} listeners)'.format(
-                    self.name, newValue, valid, len(listeners)))
-
-        # if the new value is valid, save
-        # it as the last known good value
-        try:
-            self.tkProp.validate(self.owner, newValue)
-            self.lastValue = newValue
-
-        except ValueError:
-            valid = False
-
-        # Notify all listeners about the change, ignoring
-        # any errors - it is up to the listeners to ensure
-        # that they handle invalid values
+        if value == '': value = None
+
+        return value
+        
+
+    def validateAndNotify(self):
+        """
+        Passes the current variable value to the validate()
+        method of the PropertyBase object which owns this
+        TkVarProxy, and then notifies any listeners which
+        have been registered with this TkVarProxy object.
+        """
+        
+        value     = self._getVarValue()
+        valid     = True
+        listeners = self.changeListeners.items()
+
+        try:               self.tkProp.validate(self.owner, value)
+        except ValueError: valid = False
+
+        # Notify all listeners, ignoring any errors -
+        # it is up to the listeners to ensure that
+        # they handle invalid values
         for (name,func) in listeners:
 
             log.debug('Notifying listener on {}: {}'.format(self.name, name))
             
-            try: func(newValue, valid, self.owner, self.tkProp, self.name)
+            try: func(value, valid, self.owner, self.tkProp, self.name)
             except Exception as e:
                 log.debug('Listener on {} ({}) raised exception: {}'.format(
                     self.name, name, e))
 
-
-    def revert(self):
+        
+    def _traceCb(self, *args):
         """
-        Sets the Tk variable to its last known good value. This will
-        result in any registered listeners being notified of the change.
+        Called whenever the Tkinter control variable value is changed.
+        Notifies any registered listeners, and the HasProperties
+        property owner, of the change.
         """
-        self.tkVar.set(self.lastValue)
+        
+        newValue = self._getVarValue()
+
+        log.debug('Variable {} changed: {}'.format(self.name, newValue))
+
+        # Validate the new value and notify any registered listeners
+        self.validateAndNotify()
+            
+        # Notify the property owner that this property has changed
+        self.owner._propChanged(self.tkProp)
 
 
     def __del__(self):
@@ -337,7 +338,7 @@ class PropertyBase(object):
                           returns True or False.
         
           - validateFunc: Custom validation function. Must accept
-                          two parameters:a reference to the
+                          two parameters: a reference to the
                           HasProperties instance, the owner of
                           this property; and the new property
                           value. Should raise a ValueError if the
@@ -393,7 +394,7 @@ class PropertyBase(object):
             varProxies = [varProxies]
 
         for var in varProxies:
-            var._traceCb()
+            var.validateAndNotify()
 
         
     def _varChanged(self, value, valid, instance, tkProp, name):
@@ -487,7 +488,7 @@ class PropertyBase(object):
         instval = instance.__dict__.get(self.label, None)
         if instval is None: instval = self._makeTkVar(instance)
 
-        # See comments in TkVarProxy._traceCb
+        # See comments in TkVarProxy._getVarValue
         # for a brief overview of this silliness.
         try:    val = instval.tkVar.get()
         except: val = instval.tkVar._tk.globalgetvar(instval.tkVar._name)
@@ -503,6 +504,8 @@ class PropertyBase(object):
         the given value.  
         """
 
+        # See comments in TkVarProxy._getVarValue
+        # for a brief overview of this silliness. 
         if value is None: value = ''
 
         instval = self.getTkVar(instance)
@@ -576,8 +579,8 @@ class HasProperties(object):
         propNames, props = zip(*props)
 
         return propNames, props
-        
 
+        
     def validateAll(self):
         """
         Validates all of the properties of this HasProperties object.
@@ -603,6 +606,24 @@ class HasProperties(object):
         return errors
 
         
+    def _propChanged(self, cProp):
+        """
+        Called whenever any property value changes. Forces validation
+        for all other properties, and notification of their registered
+        listeners. This is done because the validity of some
+        properties may be dependent upon the values of others. So when
+        a particular property value changes, it may ahve changed the
+        validity of another property, meaning that the listeners of
+        the latter property need to be notified of this change in
+        validity.
+        """
+        propNames, props = self.getAllProperties()
+
+        for prop in props:
+            if prop == cProp: continue
+            prop.forceValidation(self)
+        
+        
     def __str__(self):
         """
         Returns a multi-line string containing the names and values

tkprop/widgets.py

@@ -68,7 +68,11 @@ def _setupValidation(widget, propObj, tkProp, tkVar):
         of the new value.
         """
         _setBG(valid)
-        
+
+    # We add a callback listener to the Tk variable, rather than
+    # to the property, as one property may be associated with
+    # multiple variables, and we don't want the widgets associated
+    # with those other variables to change background.
     listenerName = 'ChangeBGOnValidate_{}'.format(tkVar.name)
     tkVar.addListener(listenerName, _changeBGOnValidate)