How do I annotate types in a for-loop

grepcake picture grepcake · Jan 13, 2017 · Viewed 22.3k times · Source

I want to annotate a type of a variable in a for-loop. I tried this:

for i: int in range(5):
    pass

But it didn't work, obviously.

What I expect is working autocomplete in PyCharm 2016.3.2. Pre-annotation like this:

i: int
for i in range(5):
    pass

doesn't help.

P.S. Pre-annotation works for PyCharm >= 2017.1

Answer

alecxe picture alecxe · Jan 13, 2017

According to PEP 526, this is not allowed:

In addition, one cannot annotate variables used in a for or with statement; they can be annotated ahead of time, in a similar manner to tuple unpacking

Annotate it before the loop:

i: int
for i in range(5):
    pass

PyCharm 2018.1 and up now recognizes the type of the variable inside the loop. This was not supported in older PyCharm versions.