Simple example for Param Panel class interactions

example.py

## Run it on jupyter notebook for interactive panel
import param as pm
import panel as pn

class A(pm.Parameterized):
    a = pm.Number(2)

class B(pm.Parameterized):
    def __init__(self, a:A, **params):
        super().__init__(**params)
        self.a = a
        
    b = pm.Number(2)
    
    @pm.depends('a.a', 'b')
    def sum(self):
        return self.a.a + self.b
    
a = A()
b = B(a)

pn.Column(a, b, b.sum)
## Result
## changing parameter a and b should reflect change in sum

Good base case to remember.