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 
- possible duplicate of Python `if x is not None` or `if not x is None`?ha9u63a7– ha9u63a72014-11-12 09:22:38 +00:00Commented Nov 12, 2014 at 9:22
- It's not a duplicate of that, at all.Ffisegydd– Ffisegydd2014-11-12 09:22:59 +00:00Commented Nov 12, 2014 at 9:22
- 1You have a typo in your post which @UriAgassi has decided to fix without knowing if it was broken or not, could you please check that the code as edited is what you actually have?Ffisegydd– Ffisegydd2014-11-12 09:25:54 +00:00Commented Nov 12, 2014 at 9:25
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2 Answers
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, i.e. 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.
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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
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twasbrillig
except without an Exception is too broad for general usage. It can catch anything, even Control-C! I think that except (TypeError, ValueError): would be appropriate here.