mypypath：找不到名为“ tzwhere”的模块

Question

I am learning mypy, and the first error I got is cannot find module .

My file is:

from tzwhere import tzwhere
tzw = tzwhere.tzwhere()
print(tzw)

It is runnable by python because tzwhere package is installed. But when I run it through mypy I get this:

mypy mp.py
mp.py:1: error: Cannot find module named 'tzwhere'
mp.py:1: note: (Perhaps setting MYPYPATH or using the "--ignore-missing-imports" flag would help)

How do I make it say No library stub file for module 'tzwhere' and deal with stub files instead of Cannot find module ?

Answer 1

In order for mypy (and other PEP 484 compliant tools) to understand how to type a given module, it must be able to find stubs for that module somewhere.

Mypy (if we simplify slightly) checks essentially two different places for stubs:

1. It checks a local copy of typeshed , which is a repository of type hints for the standard library and popular 3rd party libraries. (A copy of typeshed is automatically installed alongside mypy.)
2. It checks if the package itself is bundling type hints (eg if the package is a PEP 561 compliant package).

Unfortunately, it seems that tzwhere is doing neither of these things: I can't find it on typeshed; it doesn't appear to be bundling types. As a result, mypy will not be able to accurately type check code using tzwhere.

You have three main options:

1. Just suppress the error message by adding a # type: ignore annotation to the import. Note that this will introduce some dynamism into your code: any variable/function you use from tzwhere will be assumed to be of type Any .
2. Create type stubs for the module, store it in a folder somewhere, and point the MYPYPATH environment variable at that folder. Note that this will require a little bit of detective work on your part. More details on how mypy finds imports here .
3. If you want to share your work from step 2 with others, either submit a pull request to typeshed with your stubs or submit a pull request with tzwhere itself to turn it into a PEP 561 compliant package. Make sure you get an ok from the author of the library before doing either of these things.