Question

I don’t understand why not empty strings are False, same like empty strings. I think that collection of characters is much something than less. What is a root of python purpose in this case?

>>> "" in 'fdsa'
True
>>> '' in ''
True
>>> 'asdf' in ''
False
>>> 'adsf' is True
False

Answer 1

I don’t quite get your question. You are using two operators here:

1. in for strings checks whether the first string is a substring of the second. The empty string is considered a substring of every other string.

2. is tests for object identity and returns True if both operators are the same object. 'adsf' and True clearly aren’t the same object, so you get False.

None of those two operators are related to interpreting strings in a Boolean context – something your question also seems to touch on. A Boolean context would be the condition of an if statement, for example. In a Boolean context, empty strings are treated as False, and non-empty strings as True. You can see how an object behaves in a Boolean context by using bool(obj).