QTaurusBaseListener

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class QTaurusBaseListener(name=None, parent=None)

Bases: taurus.core.tauruslistener.TaurusListener

Base class for QObjects listening to taurus events.

Note

getSignaller() is now unused and deprecated. This is because taurusEvent is implemented using baseSignal(), that doesn’t require the class to inherit from QObject.

eventReceived(evt_src, evt_type, evt_value)

The basic implementation of the event handling chain is as follows:

• eventReceived just calls fireEvent() which emits a “taurusEvent” PyQt signal that is connected (by preAttach()) to the filterEvent() method.
• After filtering, handleEvent() is invoked with the resulting filtered event

Note

in the earlier steps of the chain (i.e., in eventReceived()/fireEvent()), the code is executed in a Python thread, while from eventFilter ahead, the code is executed in a Qt thread. When writing widgets, one should normally work on the Qt thread (i.e. reimplementing handleEvent())

Parameters:

• evt_src (object) – object that triggered the event
• evt_type (TaurusEventType) – type of event
• evt_value (object) – event value

filterEvent(evt_src=-1, evt_type=-1, evt_value=-1)

The event is processed by each and all filters in strict order unless one of them returns None (in which case the event is discarded)

Parameters:

• evt_src (object) – object that triggered the event
• evt_type (TaurusEventType) – type of event
• evt_value (object) – event value

fireEvent(evt_src=None, evt_type=None, evt_value=None)

Emits a “taurusEvent” signal. It is unlikely that you may need to reimplement this method in subclasses. Consider reimplementing eventReceived() or handleEvent() instead depending on whether you need to execute code in the python or Qt threads, respectively

Parameters:

• evt_src (object or None) – object that triggered the event
• evt_type (TaurusEventType or None) – type of event
• evt_value (object or None) – event value

getEventFilters()

Returns the list of event filters for this widget

Return type:sequence <callable> Returns:the event filters

getSignaller(**kwargs)

Deprecated since version 4.0.

handleEvent(evt_src, evt_type, evt_value)

Event handling. Default implementation does nothing. Reimplement as necessary

Parameters:

• evt_src (object or None) – object that triggered the event
• evt_type (TaurusEventType or None) – type of event
• evt_value (object or None) – event value

insertEventFilter(filter, index=-1)

insert a filter in a given position

Parameters:

• filter (callable(evt_src, evt_type, evt_value) – ) a filter
• index (int) – index to place the filter (default = -1 meaning place at the end)

See also: setEventFilters

setEventFilters(filters=None)

sets the taurus event filters list. The filters are run in order, using each output to feed the next filter. A filter must be a function that accepts 3 arguments (evt_src, evt_type, evt_value) If the event is to be ignored, the filter must return None. If the event is not to be ignored, filter must return a (evt_src, evt_type, evt_value) tuple which may (or not) differ from the input.

For a library of common filters, see taurus/core/util/eventfilters.py

Parameters:filters (sequence) – a sequence of filters

See also: insertEventFilter

taurusEvent

Base signal taurusEvent