Signal

Signals are a simple pub-sub mechanism.

DOMNodes can subscribe to a signal, which will invoke a callback when the signal is published.

This is experimental for now, for internal use. It may be part of the public API in a future release.

Signal `class` ¶

def __init__(self, owner, name):

A signal that a widget may subscribe to, in order to invoke callbacks when an associated event occurs.

Parameter	Default	Description
`owner` `DOMNode`	required	The owner of this signal.
`name` `str`	required	An identifier for debugging purposes.

def publish(self):

Publish the signal (invoke subscribed callbacks).

def subscribe(self, node, callback):

Subscribe a node to this signal.

When the signal is published, the callback will be invoked.

Parameter	Default	Description
`node` `DOMNode`	required	Node to subscribe.
`callback` `IgnoreReturnCallbackType`	required	A callback function which takes no arguments, and returns anything (return type ignored).

Type	Description
`SignalError`	Raised when subscribing a non-mounted widget.

def unsubscribe(self, node):

Unsubscribe a node from this signal.

Parameter	Default	Description
`node` `DOMNode`	required	Node to unsubscribe,

Raised for Signal errors.