是否有一个python内置函数来获得0为None

Question

Is there a built-in function in python which does the following:

def none_safe(int_value):
    return int_value if int_value is not None else 0

Answer 1

Assuming that the only possible inputs are None and instances of int :

int_value or 0

Some APIS, such as dict.get , have an argument where you can pass the default. In this case it's just a value, but note that or is evaluated lazily whereas a function argument is necessarily evaluated eagerly.

Other APIs, such as the constructor of collections.defaultdict , take a factory to construct defaults, ie you would have to pass lambda: 0 (or just int since that is also a callable that returns 0 ), which avoids the eagerness if that's a problem, as well as the possibility of other falsy elements.

Answer 2

Even safer (usually) is to just return 0 for any value that can't be an int

def none_safe(int_value):
    try:
        return int(int_value)
    except (TypeError, ValueError):
        return 0

Other variations might use isinstance or similar depending on your exact requirements