# HG changeset patch
# User David Douard <david.douard@logilab.fr>
# Date 1204218959 -3600
# Node ID d8bd4a931516e123ec63f58e8a8997e491620b6a
# Parent  98a94ec5f24ea9200b996461da9f5b9cd20dfc21
Make it possible to disable the cache mecanism temporarly and make AbstractCommand derivated classes not considered as commands if their name starts with '_'.

diff -r 98a94ec5f24e -r d8bd4a931516 pygpibtoolkit/gpibcontroller.py
--- a/pygpibtoolkit/gpibcontroller.py	Thu Feb 28 18:13:55 2008 +0100
+++ b/pygpibtoolkit/gpibcontroller.py	Thu Feb 28 18:15:59 2008 +0100
@@ -13,10 +13,18 @@
 
 class AbstractGPIBDeviceMetaclass(type):
     def __new__(mcs, name, bases, classdict):
+        # Automatically add commands to Device classes.
+        # Commands which name starts with '_' are ignored.
+        # Only commands defined in the same module as the device
+        # are added to the device.
+        # Commands are descriptors (see pygpib.py)
         new_cls = type.__new__(mcs, name, bases, classdict)
-        module = sys.modules[new_cls.__module__]
-        for pname, param in module.__dict__.items():            
-            if isclass(param) and issubclass(param, AbstractCommand) and param.__module__ == new_cls.__module__:
+        modname = new_cls.__module__
+        module = sys.modules[modname]
+        for pname, param in module.__dict__.items():
+            if not pname.startswith('_') and isclass(param) and \
+                    issubclass(param, AbstractCommand) and \
+                    param.__module__ == modname:
                 setattr(new_cls, pname, param())
         return new_cls
 
@@ -33,24 +41,29 @@
         self._idn = idn
         self._address = address
         self._controller = controller
-
+        self._use_cache = True
+        
         self._cache = {}
         for pname, param in self.__class__.__dict__.items():
             if isinstance(param, AbstractCommand) and not param._readonly:
                 self._cache[pname] = param._init_value
+    def use_cache(self, use=None):
+        if use is None:
+            return self._use_cache
+        self._use_cache = bool(use)
         
     def _get(self, name):
+        if self._use_cache and name in self._cache and self._cache[name] is not None:
+            return self._cache[name]
+        
+        param = getattr(self.__class__, name) 
+        cmd = param.build_get_cmd()
+        value = self._controller.send_command(self._address, cmd)
+        value = param.convert_from(value)
         if name in self._cache:
-            if self._cache[name] is None:
-                # where to get the info?
-                # ... compute value
-                param = getattr(self.__class__, name) 
-                cmd = param.build_get_cmd()
-                value = self._controller.send_command(self._address, cmd)
-                value = param.convert_from(value)
-                self._cache[name] = value
-            return self._cache[name]
-
+            self._cache[name] = value
+        return value
+            
     def _set(self, name, value):
         param = getattr(self.__class__, name) 
         cmd = param.build_set_cmd(value)