Example of refactoring using rope library.

tools/telemetry/third_party/rope/rope/base/resourceobserver.py

+import os
+
+
+class ResourceObserver(object):
+    """Provides the interface for observing resources
+
+    `ResourceObserver`\s can be registered using `Project.
+    add_observer()`.  But most of the time `FilteredResourceObserver`
+    should be used.  `ResourceObserver`\s report all changes passed
+    to them and they don't report changes to all resources.  For
+    example if a folder is removed, it only calls `removed()` for that
+    folder and not its contents.  You can use
+    `FilteredResourceObserver` if you are interested in changes only
+    to a list of resources.  And you want changes to be reported on
+    individual resources.
+
+    """
+
+    def __init__(self, changed=None, moved=None, created=None,
+                 removed=None, validate=None):
+        self.changed = changed
+        self.moved = moved
+        self.created = created
+        self.removed = removed
+        self._validate = validate
+
+    def resource_changed(self, resource):
+        """It is called when the resource changes"""
+        if self.changed is not None:
+            self.changed(resource)
+
+    def resource_moved(self, resource, new_resource):
+        """It is called when a resource is moved"""
+        if self.moved is not None:
+            self.moved(resource, new_resource)
+
+    def resource_created(self, resource):
+        """Is called when a new resource is created"""
+        if self.created is not None:
+            self.created(resource)
+
+    def resource_removed(self, resource):
+        """Is called when a new resource is removed"""
+        if self.removed is not None:
+            self.removed(resource)
+
+    def validate(self, resource):
+        """Validate the existence of this resource and its children.
+
+        This function is called when rope need to update its resource
+        cache about the files that might have been changed or removed
+        by other processes.
+
+        """
+        if self._validate is not None:
+            self._validate(resource)
+
+
+class FilteredResourceObserver(object):
+    """A useful decorator for `ResourceObserver`
+
+    Most resource observers have a list of resources and are
+    interested only in changes to those files.  This class satisfies
+    this need.  It dispatches resource changed and removed messages.
+    It performs these tasks:
+
+    * Changes to files and folders are analyzed to check whether any
+      of the interesting resources are changed or not.  If they are,
+      it reports these changes to `resource_observer` passed to the
+      constructor.
+    * When a resource is removed it checks whether any of the
+      interesting resources are contained in that folder and reports
+      them to `resource_observer`.
+    * When validating a folder it validates all of the interesting
+      files in that folder.
+
+    Since most resource observers are interested in a list of
+    resources that change over time, `add_resource` and
+    `remove_resource` might be useful.
+
+    """
+
+    def __init__(self, resource_observer, initial_resources=None,
+                 timekeeper=None):
+        self.observer = resource_observer
+        self.resources = {}
+        if timekeeper is not None:
+            self.timekeeper = timekeeper
+        else:
+            self.timekeeper = ChangeIndicator()
+        if initial_resources is not None:
+            for resource in initial_resources:
+                self.add_resource(resource)
+
+    def add_resource(self, resource):
+        """Add a resource to the list of interesting resources"""
+        if resource.exists():
+            self.resources[resource] = self.timekeeper.get_indicator(resource)
+        else:
+            self.resources[resource] = None
+
+    def remove_resource(self, resource):
+        """Add a resource to the list of interesting resources"""
+        if resource in self.resources:
+            del self.resources[resource]
+
+    def clear_resources(self):
+        """Removes all registered resources"""
+        self.resources.clear()
+
+    def resource_changed(self, resource):
+        changes = _Changes()
+        self._update_changes_caused_by_changed(changes, resource)
+        self._perform_changes(changes)
+
+    def _update_changes_caused_by_changed(self, changes, changed):
+        if changed in self.resources:
+            changes.add_changed(changed)
+        if self._is_parent_changed(changed):
+            changes.add_changed(changed.parent)
+
+    def _update_changes_caused_by_moved(self, changes, resource,
+                                        new_resource=None):
+        if resource in self.resources:
+            changes.add_removed(resource, new_resource)
+        if new_resource in self.resources:
+            changes.add_created(new_resource)
+        if resource.is_folder():
+            for file in list(self.resources):
+                if resource.contains(file):
+                    new_file = self._calculate_new_resource(
+                        resource, new_resource, file)
+                    changes.add_removed(file, new_file)
+        if self._is_parent_changed(resource):
+            changes.add_changed(resource.parent)
+        if new_resource is not None:
+            if self._is_parent_changed(new_resource):
+                changes.add_changed(new_resource.parent)
+
+    def _is_parent_changed(self, child):
+        return child.parent in self.resources
+
+    def resource_moved(self, resource, new_resource):
+        changes = _Changes()
+        self._update_changes_caused_by_moved(changes, resource, new_resource)
+        self._perform_changes(changes)
+
+    def resource_created(self, resource):
+        changes = _Changes()
+        self._update_changes_caused_by_created(changes, resource)
+        self._perform_changes(changes)
+
+    def _update_changes_caused_by_created(self, changes, resource):
+        if resource in self.resources:
+            changes.add_created(resource)
+        if self._is_parent_changed(resource):
+            changes.add_changed(resource.parent)
+
+    def resource_removed(self, resource):
+        changes = _Changes()
+        self._update_changes_caused_by_moved(changes, resource)
+        self._perform_changes(changes)
+
+    def _perform_changes(self, changes):
+        for resource in changes.changes:
+            self.observer.resource_changed(resource)
+            self.resources[resource] = self.timekeeper.get_indicator(resource)
+        for resource, new_resource in changes.moves.items():
+            self.resources[resource] = None
+            if new_resource is not None:
+                self.observer.resource_moved(resource, new_resource)
+            else:
+                self.observer.resource_removed(resource)
+        for resource in changes.creations:
+            self.observer.resource_created(resource)
+            self.resources[resource] = self.timekeeper.get_indicator(resource)
+
+    def validate(self, resource):
+        changes = _Changes()
+        for file in self._search_resource_moves(resource):
+            if file in self.resources:
+                self._update_changes_caused_by_moved(changes, file)
+        for file in self._search_resource_changes(resource):
+            if file in self.resources:
+                self._update_changes_caused_by_changed(changes, file)
+        for file in self._search_resource_creations(resource):
+            if file in self.resources:
+                changes.add_created(file)
+        self._perform_changes(changes)
+
+    def _search_resource_creations(self, resource):
+        creations = set()
+        if resource in self.resources and resource.exists() and \
+           self.resources[resource] is None:
+            creations.add(resource)
+        if resource.is_folder():
+            for file in self.resources:
+                if file.exists() and resource.contains(file) and \
+                   self.resources[file] is None:
+                    creations.add(file)
+        return creations
+
+    def _search_resource_moves(self, resource):
+        all_moved = set()
+        if resource in self.resources and not resource.exists():
+            all_moved.add(resource)
+        if resource.is_folder():
+            for file in self.resources:
+                if resource.contains(file):
+                    if not file.exists():
+                        all_moved.add(file)
+        moved = set(all_moved)
+        for folder in [file for file in all_moved if file.is_folder()]:
+            if folder in moved:
+                for file in list(moved):
+                    if folder.contains(file):
+                        moved.remove(file)
+        return moved
+
+    def _search_resource_changes(self, resource):
+        changed = set()
+        if resource in self.resources and self._is_changed(resource):
+            changed.add(resource)
+        if resource.is_folder():
+            for file in self.resources:
+                if file.exists() and resource.contains(file):
+                    if self._is_changed(file):
+                        changed.add(file)
+        return changed
+
+    def _is_changed(self, resource):
+        if self.resources[resource] is None:
+            return False
+        return self.resources[resource] != \
+            self.timekeeper.get_indicator(resource)
+
+    def _calculate_new_resource(self, main, new_main, resource):
+        if new_main is None:
+            return None
+        diff = resource.path[len(main.path):]
+        return resource.project.get_resource(new_main.path + diff)
+
+
+class ChangeIndicator(object):
+
+    def get_indicator(self, resource):
+        """Return the modification time and size of a `Resource`."""
+        path = resource.real_path
+        # on dos, mtime does not change for a folder when files are added
+        if os.name != 'posix' and os.path.isdir(path):
+            return (os.path.getmtime(path),
+                    len(os.listdir(path)),
+                    os.path.getsize(path))
+        return (os.path.getmtime(path),
+                os.path.getsize(path))
+
+
+class _Changes(object):
+
+    def __init__(self):
+        self.changes = set()
+        self.creations = set()
+        self.moves = {}
+
+    def add_changed(self, resource):
+        self.changes.add(resource)
+
+    def add_removed(self, resource, new_resource=None):
+        self.moves[resource] = new_resource
+
+    def add_created(self, resource):
+        self.creations.add(resource)