Usage of arithmetic operations on bool values True and False

Question

In python, there is such a feature - True and False can be added, subtracted, etc

Are there any examples where this can be useful?

Is there any real benefit from this feature, for example, when:

• it increases productivity
• it makes the code more concise (without losing speed) etc

Answer 1

While in most cases it would just be confusing and completely unwarranted to (ab)use this functionality, I'd argue that there are a few cases that are exceptions.

One example would be counting. True casts to 1 , so you can count the number of elements that pass some criteria in this fashion, while remaining concise and readable. An example of this would be:

valid_elements = sum(is_valid(element) for element in iterable)

As mentioned in the comments, this could be accomplished via:

valid_elements = list(map(is_valid, iterable)).count(True)

but to use .count(...) , the object must be a list, which imposes a linear space complexity (iterable may have been a constant space generator for all we know).

Another case where this functionality might be usable is as a play on the ternary operator for sequences, where you either want the sequence or an empty sequence depending on the value. Say you want to return the resulting list if a condition holds, otherwise an empty list:

return result_list * return_empty

or if you are doing a conditional string concatentation

result = str1 + str2 * do_concatenate

of course, both of these could be solved by using python's ternary operator:

return [] if return_empty else result_list
...
result = str1 + str2 if do_concatenate else str1

The point being, this behavior does provide other options in a few scenarios that isn't all too unreasonable. Its just a matter of using your best judgement as to whether it'll cause confusion for future readers (yourself included).

Answer 2

I would avoid it at all cost. It is confusing and goes against typing. Python being permissive does not mean you should do it ...