When parameters are passed as arguments to a class instantiation then they don’t trigger events.
For example:
class Demo(param.Parameterized):
upper_bound = param.Integer(default=10)
my_range = param.Range(default=(0, upper_bound.default), bounds=(0, upper_bound.default))
@param.depends('upper_bound', watch=True)
def update_bounds(self):
self.param.my_range.bounds = (0, self.upper_bound)
def panel(self):
return pn.Param(self)
d = Demo(upper_bound=20)
d.panel()
In this example even though upper_bound is passed in the the Demo constructor, it doesn’t trigger the update_bounds method.
One way to ensure that it triggers is to set upper_bound after instantiation:
d = Demo()
d.upper_bound = 20
But is the only way to ensure that the method is triggered on instantiation by calling it in an init method?
class Demo(param.Parameterized):
upper_bound = param.Integer(default=10)
my_range = param.Range(default=(0, upper_bound.default), bounds=(0, upper_bound.default))
def __init__(self, **params):
super().__init__(**params)
if self.upper_bound != self.param.upper_bound.default: # Sometimes this matters
self.update_bounds()
@param.depends('upper_bound', watch=True)
def update_bounds(self):
self.param.my_range.bounds = (0, self.upper_bound)
def panel(self):
return pn.Param(self)
d = Demo(upper_bound=20)
d.panel()