Question

I’m a new member here and also new to python. My question is as follows, is it valid to have a line like this?

if x or y is 'whatever':

I tested this in the interpreter and am getting inconsistent results. It would seem that this line yields more consistent and expected results

if (x or y) is 'whatever':

Or is it always best to explicitly have everything laid out as such

if x is 'whatever' or y is 'whatever':

This last one always works but I’m just trying to make my code a bit more concise while still following best practices. I tried doing a search so as not to ask a redundant question but searching for ‘is’ ‘or’ and ‘and’ is rather difficult. Thanks in advance for any assistance.

edit: Thanks all for the quick replies. This works perfectly for me when I need ‘or’

if 'whatever' in [x,y]:

But how would I condense this if I need an ‘and’?

if x == 'whatever' and y == 'whatever':

Answer 1

or doesn’t work like it does in English.

x or y returns x if x is a true-ish value, otherwise it returns y. Strings are true-ish if they are not empty.

Worse, “is” has a higher precedence that “or”, so your expression is the same as x or (y is 'whatever'). So if x is not empty, it returns x (which will be true, so the if will execute). If x is empty, it will evaluate y is 'whatever'.

BTW: Don’t use “is” to compare value equality, use ==.

You want this (parens optional):

if (x == 'whatever') or (y == 'whatever'):

or more concise, but stranger:

if 'whatever' in [x, y]: