In a param.Parameterized class, I have several parameters which are very much alike.
idealy I would want to define a single callback method decorated with param.depends and the list of parameters. But from there there is no wayt to know which object triggered the event, unlike when using .param.watch.
I end up having to make one callback per parameter decorated with param.depends.
I tried adding self.param.watch(self.callback,[ 'param1', 'param2', 'param3']) within the __init__ method, but the event is not inputted in the callback method.
The only way is to define it outside of its definition…
Where can I find the last triggered event within a Parameterized instance?
I have noticed self.param._events, but it’s always an empty list.
The param doc is not very helpful 
Second that, I often have that thought.
I would also be interested in a way to batch watch params. Noticed the param.batch_watch() function, but couldn’t get it to work the way I was expecting.
Does anyone have an example for us?
I don’t to know to which extent this snippet might help you @hyamanieu, if not it may be useful for someone else:
from param import Parameterized, Parameter, depends
class A(Parameterized):
x = Parameter(1)
y = Parameter(2)
def react(self, *events):
print(f"React to events ({len(events)}):")
for event in events:
print(f"\tTriggered by '{event.name}' now set to {event.new} (previously equal to {event.old})")
def __init__(self, **params):
super().__init__(**params)
watcher = self.param.watch(self.react, ["x", "y"])
a = A()
a.x = 10
a.y = 20
a.param.set_param(x=0, y=0)
a.param.trigger("y", "x")
2 Likes
Hello,
I don’t recall anymore why self.param.watch did not work in my case but your example looks like it’s working. I’ll keep it in mind, thanks!
