Split watchdog functionality to TodoFileWatched class

Also improve the logic to prevent updates for changes caused by the
current topydo instance. This was done to ignore the first file update
event after writing out the file, and trigger updates for all other
file updates that have to be external.

topydo/lib/TodoFile.py

@@ -28,42 +28,8 @@ class TodoFile(object):
     to.
     """
 
-    def __init__(self, p_path, p_on_update=None):
+    def __init__(self, p_path):
         self.path = os.path.abspath(p_path)
-        self.write_lock = False
-
-        if p_on_update:
-            from watchdog.observers import Observer
-            from watchdog.events import FileSystemEventHandler, FileModifiedEvent, FileCreatedEvent
-
-            class EventHandler(FileSystemEventHandler):
-                """
-                Event handler to catch modifications (or creations) of the
-                current todo.txt file.
-                """
-                def __init__(self, p_file):
-                    super().__init__()
-                    self.file = p_file
-
-                def _handle(self, p_event):
-                    right_type = isinstance(p_event, FileModifiedEvent) or isinstance(p_event, FileCreatedEvent)
-
-                    if not self.file.write_lock and right_type and p_event.src_path == self.file.path:
-                        p_on_update()
-
-                def on_created(self, p_event):
-                    """
-                    Because vim deletes and creates a file on buffer save, also
-                    catch a creation event.
-                    """
-                    self._handle(p_event)
-
-                def on_modified(self, p_event):
-                    self._handle(p_event)
-
-            observer = Observer()
-            observer.schedule(EventHandler(self), os.path.dirname(self.path))
-            observer.start()
 
     def read(self):
         """ Reads the todo.txt file and returns a list of todo items. """
@@ -85,10 +51,6 @@ class TodoFile(object):
         to the file.
         """
 
-        # make sure not to reread the todo file because this instance is
-        # actually writing it
-        self.write_lock = True
-
         todofile = codecs.open(self.path, 'w', encoding="utf-8")
 
         if p_todos is list:
@@ -100,4 +62,3 @@ class TodoFile(object):
         todofile.write("\n")
 
         todofile.close()
-        self.write_lock = False

topydo/lib/TodoFileWatched.py

+# Topydo - A todo.txt client written in Python.
+# Copyright (C) 2014 - 2016 Bram Schoenmakers <bram@topydo.org>
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+"""
+This module deals with todo.txt files while putting a watch on them for file
+changes.
+"""
+
+import os.path
+from watchdog.observers import Observer
+from watchdog.events import FileSystemEventHandler, FileModifiedEvent, FileCreatedEvent
+
+from topydo.lib.TodoFile import TodoFile
+
+
+class TodoFileWatched(TodoFile):
+    """
+    This class represents a todo.txt file, which can be read from or written
+    to.
+    """
+
+    def __init__(self, p_path, p_on_update):
+        super().__init__(p_path)
+
+        class EventHandler(FileSystemEventHandler):
+            """
+            Event handler to catch modifications (or creations) of the
+            current todo.txt file.
+            """
+            def __init__(self, p_file):
+                super().__init__()
+                self.file = p_file
+
+            def _handle(self, p_event):
+                right_type = isinstance(p_event, FileModifiedEvent) or isinstance(p_event, FileCreatedEvent)
+                should_trigger = right_type and p_event.src_path == self.file.path
+
+                if self.file.self_write and should_trigger:
+                    # the file was written by topydo, unmark that so we can
+                    # record external writes again.
+                    self.file.self_write = False
+                elif should_trigger:
+                    p_on_update()
+
+            def on_created(self, p_event):
+                """
+                Because vim deletes and creates a file on buffer save, also
+                catch a creation event.
+                """
+                self._handle(p_event)
+
+            def on_modified(self, p_event):
+                self._handle(p_event)
+
+        observer = Observer()
+        observer.schedule(EventHandler(self), os.path.dirname(self.path))
+        observer.start()
+
+    def write(self, p_todos):
+        # make sure not to reread the todo file because this instance is
+        # actually writing it
+        self.self_write = True
+        super().write(p_todos)

topydo/ui/columns/Main.py

@@ -30,7 +30,7 @@ from topydo.lib.Sorter import Sorter
 from topydo.lib.Filter import get_filter_list, RelevanceFilter, DependencyFilter
 from topydo.lib.Utils import get_terminal_size
 from topydo.lib.View import View
-from topydo.lib import TodoFile
+from topydo.lib.TodoFileWatched import TodoFileWatched
 from topydo.lib import TodoList
 from topydo.ui.CLIApplicationBase import CLIApplicationBase, error
 from topydo.ui.columns.CommandLineWidget import CommandLineWidget
@@ -115,7 +115,7 @@ class UIApplication(CLIApplicationBase):
             self._redraw()
 
         self.column_width = config().column_width()
-        self.todofile = TodoFile.TodoFile(config().todotxt(), callback)
+        self.todofile = TodoFileWatched(config().todotxt(), callback)
         self.todolist = TodoList.TodoList(self.todofile.read())
 
         self.marked_todos = []

topydo/ui/prompt/Prompt.py

@@ -37,7 +37,7 @@ except ConfigError as config_error:
     sys.exit(1)
 
 from topydo.Commands import get_subcommand
-from topydo.lib import TodoFile
+from topydo.lib.TodoFileWatched import TodoFileWatched
 from topydo.lib import TodoList
 
 
@@ -52,7 +52,7 @@ class PromptApplication(CLIApplicationBase):
 
         self._process_flags()
         self.completer = None
-        self.todofile = TodoFile.TodoFile(config().todotxt(), self._load_file)
+        self.todofile = TodoFileWatched(config().todotxt(), self._load_file)
 
     def _load_file(self):
         """