Use the class defined constant instead of raw strings

In examples and documentation it is better if we recommend
good practices for using the notifications and the good/better
practice would be to use the class defined constant instead of
using a raw string (in-case taskflow ever changes that constant
value sometime in the future).

Change-Id: Ied8fc88747f8635de4aa776095e7e0195d6043aa

4 files changed, 22 insertions, 12 deletions

diff --git a/doc/source/notifications.rst b/doc/source/notifications.rst
index 3fd35e2..c0dbe4e 100644
--- a/doc/source/notifications.rst
+++ b/doc/source/notifications.rst
@@ -7,6 +7,8 @@ Notifications and listeners
     from taskflow import task
     from taskflow.patterns import linear_flow
     from taskflow import engines
+    from taskflow.types import notifier
+    ANY = notifier.Notifier.ANY
 
 --------
 Overview
@@ -57,7 +59,7 @@ A basic example is:
    >>> flo = linear_flow.Flow("cat-dog").add(
    ...   CatTalk(), DogTalk(provides="dog"))
    >>> eng = engines.load(flo, store={'meow': 'meow', 'woof': 'woof'})
-   >>> eng.notifier.register("*", flow_transition)
+   >>> eng.notifier.register(ANY, flow_transition)
    >>> eng.run()
    Flow 'cat-dog' transition to state RUNNING
    meow
@@ -93,7 +95,7 @@ A basic example is:
    >>> flo.add(CatTalk(), DogTalk(provides="dog"))
    <taskflow.patterns.linear_flow.Flow object at 0x...>
    >>> eng = engines.load(flo, store={'meow': 'meow', 'woof': 'woof'})
-   >>> eng.task_notifier.register("*", task_transition)
+   >>> eng.task_notifier.register(ANY, task_transition)
    >>> eng.run()
    Task 'CatTalk' transition to state RUNNING
    meow
diff --git a/taskflow/examples/build_a_car.py b/taskflow/examples/build_a_car.py
index 1655f2a..02be020 100644
--- a/taskflow/examples/build_a_car.py
+++ b/taskflow/examples/build_a_car.py
@@ -31,6 +31,9 @@ import taskflow.engines
 from taskflow.patterns import graph_flow as gf
 from taskflow.patterns import linear_flow as lf
 from taskflow import task
+from taskflow.types import notifier
+
+ANY = notifier.Notifier.ANY
 
 import example_utils as eu  # noqa
 
@@ -160,11 +163,11 @@ spec = {
 
 engine = taskflow.engines.load(flow, store={'spec': spec.copy()})
 
-# This registers all (*) state transitions to trigger a call to the flow_watch
-# function for flow state transitions, and registers the same all (*) state
-# transitions for task state transitions.
-engine.notifier.register('*', flow_watch)
-engine.task_notifier.register('*', task_watch)
+# This registers all (ANY) state transitions to trigger a call to the
+# flow_watch function for flow state transitions, and registers the
+# same all (ANY) state transitions for task state transitions.
+engine.notifier.register(ANY, flow_watch)
+engine.task_notifier.register(ANY, task_watch)
 
 eu.print_wrapped("Building a car")
 engine.run()
@@ -176,8 +179,8 @@ engine.run()
 spec['doors'] = 5
 
 engine = taskflow.engines.load(flow, store={'spec': spec.copy()})
-engine.notifier.register('*', flow_watch)
-engine.task_notifier.register('*', task_watch)
+engine.notifier.register(ANY, flow_watch)
+engine.task_notifier.register(ANY, task_watch)
 
 eu.print_wrapped("Building a wrong car that doesn't match specification")
 try:
diff --git a/taskflow/examples/simple_linear_listening.py b/taskflow/examples/simple_linear_listening.py
index 04f9f14..d14c82c 100644
--- a/taskflow/examples/simple_linear_listening.py
+++ b/taskflow/examples/simple_linear_listening.py
@@ -28,6 +28,9 @@ sys.path.insert(0, top_dir)
 import taskflow.engines
 from taskflow.patterns import linear_flow as lf
 from taskflow import task
+from taskflow.types import notifier
+
+ANY = notifier.Notifier.ANY
 
 # INTRO: In this example we create two tasks (this time as functions instead
 # of task subclasses as in the simple_linear.py example), each of which ~calls~
@@ -92,8 +95,8 @@ engine = taskflow.engines.load(flow, store={
 # notification objects that a engine exposes. The usage of a '*' (kleene star)
 # here means that we want to be notified on all state changes, if you want to
 # restrict to a specific state change, just register that instead.
-engine.notifier.register('*', flow_watch)
-engine.task_notifier.register('*', task_watch)
+engine.notifier.register(ANY, flow_watch)
+engine.task_notifier.register(ANY, task_watch)
 
 # And now run!
 engine.run()
diff --git a/taskflow/examples/wbe_event_sender.py b/taskflow/examples/wbe_event_sender.py
index 38b6bfd..e5b075a 100644
--- a/taskflow/examples/wbe_event_sender.py
+++ b/taskflow/examples/wbe_event_sender.py
@@ -34,6 +34,8 @@ from taskflow import task
 from taskflow.types import notifier
 from taskflow.utils import threading_utils
 
+ANY = notifier.Notifier.ANY
+
 # INTRO: This examples shows how to use a remote workers event notification
 # attribute to proxy back task event notifications to the controlling process.
 #
@@ -94,7 +96,7 @@ WORKER_CONF = {
 
 def run(engine_options):
     reporter = EventReporter()
-    reporter.notifier.register(notifier.Notifier.ANY, event_receiver)
+    reporter.notifier.register(ANY, event_receiver)
     flow = lf.Flow('event-reporter').add(reporter)
     eng = engines.load(flow, engine='worker-based', **engine_options)
     eng.run()