rx.when not using initial value

[MarcSkovMadsen]

I was trying to document rx.when on the main branch. Since there is no example in the docs about initial argument I tried to create one. But its not working as I would expect

from param import rx

def expensive_function(a, b):
    print(f'multiplying {a=} and {b=}')
    return a * b

a = rx(1)
b = rx(2)

gate = rx(False)
gated_expr = rx(expensive_function)(a, b).rx.when(gate, initial="Initial")
assert gated_expr.rx.value=="Initial"

$ python script.py
multiplying a=1 and b=2
Traceback (most recent call last):
  File "/home/jovyan/repos/private/param/script.py", line 12, in <module>
    assert gated_expr.rx.value=="Initial"
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
AssertionError

I would expect this not to raise an error and for the expensive_function not to be evaluated.

[MarcSkovMadsen]

If the gate is a param.Event it works as expected though.

import param
from param import rx

def expensive_function(a, b):
    print(f'multiplying {a=} and {b=}')
    return a * b

a = rx(1)
b = rx(2)

class State(param.Parameterized):
    gate = param.Event()

gate = State().gate
gated_expr = rx(expensive_function)(a, b).rx.when(gate, initial="Initial")
assert gated_expr.rx.value=="Initial"