param.parameterized.Parameters.trigger

Parameters.trigger(*param_names: str) → None

Trigger watchers for the given set of parameter names.

This method invokes all watchers associated with the given parameter names, regardless of whether the parameter values have actually changed.

Parameters:

*param_names (str) – Names of the parameters to trigger. Each name must correspond to a parameter defined on this Parameterized object.

Notes

As a special case, the value will actually be changed for a Parameter of type param.Event, setting it to True so that it is clear which param.Event parameter has been triggered.

Examples

This method is useful to trigger watchers of parameters whose value is a mutable container:

>>> import param
>>> class MyClass(param.Parameterized):
...     values = param.List([1, 2])
>>> obj = MyClass()
>>> def callback(event):
...     print(f"Triggered {event.name} / {event.new}")
>>> obj.param.watch(callback, 'values')
>>> obj.values.append(3)
>>> obj.param.trigger('values')
Triggered values / [1, 2, 3]