client: add SecopClient.execCommandFromString

analogous to setParameterFromString
to be used in simple clients where values of structured datatypes
are just python literals

Change-Id: I4936a3c5c0cac45bd7e875c938ce2700b4f4a979
Reviewed-on: https://forge.frm2.tum.de/review/c/secop/frappy/+/36262
Reviewed-by: Markus Zolliker <markus.zolliker@psi.ch>
Tested-by: Jenkins Automated Tests <pedersen+jenkins@frm2.tum.de>

frappy/client/__init__.py

@@ -753,10 +753,13 @@ class SecopClient(ProxyClient):
             data = datatype.import_value(data)
         return data, qualifiers
 
-    def execCommandFromString(self, module, command, formatted_argument):
+    def execCommandFromString(self, module, command, formatted_argument=''):
         """call command from string argument
 
-        return formatted data and qualifiers
+        return data as CacheItem which allows to get
+        - result.value  # the python value
+        - result.formatted()  # a string (incl. units)
+        - result.timestamp
         """
         self.connect()
         datatype = self.modules[module]['commands'][command]['datatype'].argument
@@ -766,11 +769,11 @@ class SecopClient(ProxyClient):
             if formatted_argument:
                 raise WrongTypeError('command has no argument')
             argument = None
+        # pylint: disable=unsubscriptable-object
         data, qualifiers = self.request(COMMANDREQUEST, self.identifier[module, command], argument)[2]
         datatype = self.modules[module]['commands'][command]['datatype'].result
-        if datatype:
-            data = datatype.format_value(data)
-        return data, qualifiers
+        value = datatype.import_value(data) if datatype else None
+        return CacheItem(value, qualifiers.get('t'), None, datatype)
 
     def updateValue(self, module, param, value, timestamp, readerror):
         datatype = self.modules[module]['parameters'][param]['datatype']