Correctly annotate PIL Image(s)

[pantheraleo-7]

Currently the return types are annotated as PIL.Image (the module) and not the intended (?) PIL.Image.Image (the class). This PR rectifies that.

[pantheraleo-7]

@davidplowman is this PR missing something?

[davidplowman]

@davidplowman is this PR missing something?

Hi again, no don't think so. Can you just explain what was wrong about it previously, is it causing errors somehow? (sorry, I haven't quite understood)

[pantheraleo-7]

Yes, it is causing type checker errors.

PIL is a library (analogous to a folder)
PIL.Image is a module (an Image.py file in the PIL folder)
PIL.Image.Image is a class (this Image class represents all the PIL images, it is in the Image.py file of the PIL folder)

Currently when we return PIL images, we annotate it as PIL.Image, so the type checker assumes we are returning the module itself instead of the PIL Image. This causes all kinds of type errors.

[pantheraleo-7]

The type checker even warns us that a module cannot be annotated as a return type, but we do anyway. And this in turn causes many type checker errors in the downstream usage.

[pantheraleo-7]

This can be solved in two ways:

• we directly import the Image class using from PIL.Image import Image
• we import the module from PIL import Image (the convention) and annotate everything with the class Image.Image

[pantheraleo-7]

Before:

After:

[davidplowman]

OK, thanks for the explanation!