How does this complex expression with OR work?

Question

The line is:

key1 = dictionary_name.get('key1', ['']) [0] or 0

I understand the get method and the default value but I have no clue what's happening with the or after the ). The line seems to have the function to read the value of a key out of a directory and return 0 if the value is ' '.
But how does the line, especially the boolean or, work in details?

If the zeroth element of the result of the `get` is falsy, the result will be `0`. Otherwise, use that element. — jonrsharpe, May 18 '16 at 19:55
`or` is a lazy operator. If the first item is truthy, it'll return that. Otherwise it'll return the second value. — Morgan Thrapp, May 18 '16 at 19:55

score -1 · Answer 1 · edited May 23 '17 at 12:08

-1

The empty string is falsy in python, so in this situation, if key1 is not found, the value will be 0

Python documentation

SO example

edited May 23 '17 at 12:08

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answered May 18 '16 at 19:57

David

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score -1 · Answer 2 · answered May 18 '16 at 20:09

To quote the docs:

The expression x or y first evaluates x; if x is true, its value is returned; otherwise, y is evaluated and the resulting value is returned.

[...]

Note that neither and nor or restrict the value and type they return to False and True, but rather return the last evaluated argument.

How does this complex expression with OR work?

2 Answers2