wx.lib.pubsub.core.publisherbase.PublisherBase

Represent the class that send messages to listeners of given topics and that knows how to subscribe/unsubscribe listeners from topics.

Class Hierarchy

Inheritance diagram for class PublisherBase:

Methods Summary

__init__	If treeConfig is None, a default one is created from an
addNotificationHandler	Add a handler for tracing pubsub activity. The handler should be
clearNotificationHandlers	Remove all notification handlers that were added via
getListenerExcHandler	Get the listener exception handler that was registered
getNotificationFlags	Return a dictionary with the notification flag states.
getTopicMgr	Get the topic manager created for this publisher.
sendMessage	Send a message for topic name with given data (args and kwargs).
setListenerExcHandler	Set the function to call when a listener raises an exception
setNotificationFlags	Set the notification flags on or off for each type of
setTopicUnspecifiedFatal	Changes the creation policy for topics.
subscribe	Subscribe listener to named topic. Raises ListenerMismatchError
unsubAll	By default (no args given), unsubscribe all listeners from all
unsubscribe	Unsubscribe from given topic. Returns the pubsub.core.Listener

Class API

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class PublisherBase

Represent the class that send messages to listeners of given topics and that knows how to subscribe/unsubscribe listeners from topics.

Methods

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__init__(self, treeConfig = None)

If treeConfig is None, a default one is created from an instance of TreeConfig.

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addNotificationHandler(self, handler)

Add a handler for tracing pubsub activity. The handler should be a class that adheres to the API of INotificationHandler.

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clearNotificationHandlers(self)

Remove all notification handlers that were added via self.addNotificationHandler().

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getListenerExcHandler(self)

Get the listener exception handler that was registered via setListenerExcHandler(), or None of none registered.

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getNotificationFlags(self)

Return a dictionary with the notification flag states.

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getTopicMgr(self)

Get the topic manager created for this publisher.

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sendMessage(self, topicName, *args, **kwargs)

Send a message for topic name with given data (args and kwargs). This will be overridden by derived classes that implement message-sending for different messaging protocols; not all parameters may be accepted.

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setListenerExcHandler(self, handler)

Set the function to call when a listener raises an exception during a sendMessage(). The handler must adhere to the IListenerExcHandler API.

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setNotificationFlags(self, **kwargs)

Set the notification flags on or off for each type of pubsub activity. The kwargs keys can be any of the following:

• subscribe: if True, get notified whenever a listener subscribes to a topic;
• unsubscribe: if True, get notified whenever a listener unsubscribes from a topic;
• deadListener: if True, get notified whenever a subscribed listener has been garbage-collected;
• sendMessage: if True, get notified whenever sendMessage() is called;
• newTopic: if True, get notified whenever a new topic is created;
• delTopic: if True, get notified whenever a topic is “deleted” from topic tree;
• all: set all of the above to the given value (True or False).

The kwargs that are None are left at their current value. Those that are False will cause corresponding notification to be silenced. The ‘all’ is set first, then the others. E.g.

mgr.setFlagStates(all=True, delTopic=False)

will toggle all notifications on, but will turn off the ‘delTopic’ notification.

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setTopicUnspecifiedFatal(self, newVal=True, checkExisting=True)

Changes the creation policy for topics.

By default, pubsub will accept topic names for topics that don’t have a message data specification (MDS). This default behavior makes pubsub easier to use initially, but allows topic names with typos to go uncaught in common operations such as sendMessage() and subscribe(). In a large application, this can lead to nasty bugs. Pubsub’s default behavior is equivalent to setTopicUnspecifiedFatal(false).

When called with newVal=True, any future pubsub operation that requires a topic (such as subscribe and sendMessage) will require an MDS; if none is available, pubsub will raise a TopicDefnError exception.

If checkExisting is not given or True, all existing topics are validated. A TopicDefnError exception is raised if one is found to be incomplete (has hasMDS() false).

Returns previous value of newVal.

Note that this method can be used in several ways:

1. Only use it in your application when something is not working as expected: just add a call at the beginning of your app when you have a problem with topic messages not being received (for instance), and remove it when you have fixed the problem.
2. Use it from the beginning of your app and never use newVal=False: add a call at the beginning of your app and you leave it in (forever), and use Topic Definition Providers to provide the listener specifications. These are easy to use via the pub.addTopicDefnProvider().
3. Use it as in #1 during app development, and once stable, use #2. This is easiest to do in combination with pub.exportTopicTreeSpec().

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subscribe(self, listener, topicName)

Subscribe listener to named topic. Raises ListenerMismatchError if listener isn’t compatible with the topic’s MDS. Returns (pubsub.core.Listener, success), where success is False if listener was already subscribed. The pub.core.Listener wraps the callable subscribed and provides introspection-based info about the callable.

Note that if ‘subscribe’ notification is on, the handler’s ‘notifySubscribe’ method is called after subscription.

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unsubAll(self, topicName = None, listenerFilter = None, topicFilter = None)

By default (no args given), unsubscribe all listeners from all topics. A listenerFilter can be given so that only the listeners that satisfy listenerFilter(listener) == True will be unsubscribed (with listener being a pub.Listener wrapper instance for each listener subscribed). A topicFilter can also be given so that only topics that satisfy topicFilter(topic name) == True will be affected. If only one topic should have listeners unsubscribed, then a topic name ‘topicName’ can be given instead instead of a topic filter.

Returns the list of all listeners (instances of pub.Listener) that were unsubscribed from the topic tree).

Note: this method will generate one ‘unsubcribe’ notification message (see pub.setNotificationFlags()) for each listener unsubscribed.

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unsubscribe(self, listener, topicName)

Unsubscribe from given topic. Returns the pubsub.core.Listener instance that was used to wrap listener at subscription time. Raises an TopicNameError if topicName doesn’t exist.

Note that if ‘unsubscribe’ notification is on, the handler’s notifyUnsubscribe() method will be called after unsubscribing.