frappy.client.interactive: improve order of callbacks

the user would expect that updates are shown in the order
they appeared in the SECoP connection.
For this register_callback needs an additional parameter
to suppress initial callback.

Change-Id: Id1d7605d739b02ec799b3768ae2399558969c381

frappy/client/__init__.py

@@ -188,7 +188,7 @@ class ProxyClient:
         # caches (module, parameter) = value, timestamp, readerror (internal names!)
         self.cache = Cache()  # dict returning Cache.undefined for missing keys
 
-    def register_callback(self, key, *args, **kwds):
+    def register_callback(self, key, *args, callimmediately=None, **kwds):
         """register callback functions
 
         - key might be either:
@@ -206,7 +206,7 @@ class ProxyClient:
                 raise TypeError(f"unknown callback: {', '.join(kwds)}")
 
             # immediately call for some callback types
-            if cbname in ('updateItem', 'updateEvent'):
+            if cbname in ('updateItem', 'updateEvent') and callimmediately is not False:
                 if key is None:  # case generic callback
                     cbargs = [(m, p, d) for (m, p), d in self.cache.items()]
                 else:

frappy/client/interactive.py

@@ -216,14 +216,16 @@ class Module:
     def __call__(self, target=None):
         if target is None:
             return self.read()
+        for pname in 'value', 'status':
+            self._secnode.register_callback((self._name, pname),
+                                            callimmediately=False,
+                                            updateEvent=self._watch_parameter)
+
         self.target = target  # this sets self._is_driving
-        type(self).value.prev = None  # show at least one value
 
         def loop():
             while self._is_driving:
                 self._driving_event.wait()
-                self._watch_parameter(self._name, 'value', mininterval=self._secnode.mininterval)
-                self._watch_parameter(self._name, 'status')
                 self._driving_event.clear()
         try:
             loop()
@@ -237,9 +239,11 @@ class Module:
                 pass
             clientenv.raise_with_short_traceback(e)
         finally:
-            self._watch_parameter(self._name, 'status')
+            # self._watch_parameter(self._name, 'status')
             self._secnode.readParameter(self._name, 'value')
-            self._watch_parameter(self._name, 'value', forced=True)
+            # self._watch_parameter(self._name, 'value', forced=True)
+            self._secnode.unregister_callback((self._name, 'value'), updateEvent=self._watch_parameter)
+            self._secnode.unregister_callback((self._name, 'status'), updateEvent=self._watch_parameter)
         return self.value
 
     def __repr__(self):