firstval¶

emlib.misc.firstval(*values, sentinel=None)[source]¶

Get the first value in values which is not sentinel.

At least one of the values should differ from sentinel, otherwise an exception is raised. To allow short-cirtcuit lazy evaluation, a callable can be given as value, in which case the function will only be evaluated if the previous values where sentinel

Example

config = {'a': 10, 'b': 20}
def func(a=None, b=None):
    a = firstval(a, lambda: computation(), config['a'])