Why does checking for Nulls in my function's parameter always return None?

Asked Aug 17 '22 at 19:39

Active Aug 17 '22 at 19:40

Viewed 28 times

from datetime import date 
from datetime import datetime


def get_time_delta(comic1,comic2):
    if comic1 or comic2 is type(None):
        dict1 = comic1["day"],comic1["month"],comic1["year"]
        dict2 = comic1["day"],comic1["month"],comic1["year"]

        date_one = date(comic1["year"],comic1["month"],comic1["day"]) 
        date_two = date(comic2["year"],comic2["month"],comic2["day"]) 
        difference = date_two - date_one 
    else:
        return None
    

comic1, comic2 = get_all_comics(513, 514)  
print(get_time_delta(comic1,comic2))

I want the function to return None if parameter1(comic1) or parameter2 (comic2) is None. However I phrase the sentence, it just always returns None.

The last part, using the function "get_all_comics(513,514)" returns one dict each for each of the two numbers, which I then pass into the get_time_delta function.

I suspect it has something to do with Python not defining the parameters as dictionaries until later in the code, but im not knowledgeable enough in Python to know exactly how it does this.

edited Aug 17 '22 at 19:40

asked Aug 17 '22 at 19:39

Inthemaking

3

`if comic1 or comic2 is type(None):` isn't doing what you think it's doing. – MattDMo Aug 17 '22 at 19:41
1

Besides wrong use of `or`, also note that `None != type(None)` – tobias_k Aug 17 '22 at 19:42
instead of doing `var is type(None)`, try `var is None`, or better yet: `not var`. – rv.kvetch Aug 17 '22 at 19:43
Additionally, your function only returns in the `else` clause. You should probably change that. – MattDMo Aug 17 '22 at 19:43
Right. Use `if not comic1 or not comic2:`, or even `if comic1 is None or comic2 is None:`, if other falsy values are possible. – Tim Roberts Aug 17 '22 at 19:43
And you can delete the `else` clause. A function without a return statement already returns None. – Tim Roberts Aug 17 '22 at 19:44
Welcome the feedback. Any suggestions to what I can look into? – Inthemaking Aug 17 '22 at 19:44
@tobias_k Can you explain how this is wrong use of or? – Inthemaking Aug 17 '22 at 19:45
@rv.kvetch I tried that first. Still returns None – Inthemaking Aug 17 '22 at 19:47
@TimRoberts I was not aware of that. Thanks for this! – Inthemaking Aug 17 '22 at 19:48

Why does checking for Nulls in my function's parameter always return None?

0 Answers0