Add ADSObserver for MSlice

Author: SilkeSchomann

src/mslice/models/mslice_ads_observer.py

@@ -0,0 +1,77 @@
+from functools import wraps
+import sys
+
+from mantid.api import AnalysisDataServiceObserver
+
+
+def _catch_exceptions(func):
+    """
+    Catch all exceptions in method and print a traceback to stderr
+    """
+
+    @wraps(func)
+    def wrapper(*args, **kwargs):
+        try:
+            func(*args, **kwargs)
+        except Exception:
+            sys.stderr.write("Error occurred in handler:\n")
+            import traceback
+
+            traceback.print_exc()
+
+    return wrapper
+
+
+class MSliceADSObserver(AnalysisDataServiceObserver):
+    def __init__(self, delete_callback, clear_callback, replace_callback, rename_callback):
+        super(MSliceADSObserver, self).__init__()
+        self.delete_callback = delete_callback
+        self.clear_callback = clear_callback
+        self.replace_callback = replace_callback
+        self.rename_callback = rename_callback
+
+        self.observeDelete(True)
+        self.observeRename(True)
+        self.observeReplace(True)
+        self.observeClear(True)
+
+    @_catch_exceptions
+    def deleteHandle(self, workspace_name, workspace):
+        """
+        Called when the ADS deletes a workspace, removes it from the dict of tracked workspaces.
+        :param workspace_name: name of the workspace
+        :param workspace: reference to the workspace (not used)
+        """
+        self.delete_callback(workspace_name)
+
+    @_catch_exceptions
+    def renameHandle(self, old_workspace_name, new_workspace_name):
+        """
+        Called when the ADS renames a workspace, updates the dict with the new name.
+        :param old_workspace_name: original name of the workspace
+        :param new_workspace_name: new name for the workspace
+        """
+        self.rename_callback(old_workspace_name, new_workspace_name)
+
+    @_catch_exceptions
+    def clearHandle(self):
+        """
+        Called when the ADS has been cleared, removes all data.
+        """
+        self.clear_callback()
+
+    @_catch_exceptions
+    def replaceHandle(self, name, workspace):
+        """
+        Called when the ADS has replaced a workspace with one of the same name.
+        Updates the workspace stored in the dict.
+        :param name: The name of the workspace.
+        :param workspace: A reference to the new workspace
+        """
+        self.replace_callback(name, workspace)
+
+    def unsubscribe(self):
+        self.observeDelete(False)
+        self.observeRename(False)
+        self.observeClear(False)
+        self.observeReplace(False)