Andor CCD DU401 driver

[lankes-fzj]

New driver for 'Andor CCD DU401'

(based on SvenBo90/Qcodes@2cff137)

[astafan8]

@lankes-fzj see commit e8344e0 about WinDLL type annotation and sys.platform usage. Otherwise type checking with mypy fails the CI.

[lankes-fzj]

Do you have any idea, why mypy fails with the error "Cannot determine type of 'dll'"? This didn't happen to PRs #28 and #29, although they are working the same way...

[jenshnielsen]

I am not sure but I suggest that you just put an assert sys.platform == 'win32' at the top of the file just after the imports as suggested here https://mypy.readthedocs.io/en/stable/common_issues.html#python-version-and-system-platform-checks

[lankes-fzj]

I am not sure but I suggest that you just put an assert sys.platform == 'win32' at the top of the file just after the imports as suggested here https://mypy.readthedocs.io/en/stable/common_issues.html#python-version-and-system-platform-checks

But then the tests would fail on linux, wouldn't they?

[jenshnielsen]

Which tests? As documented in the link above this will make mypy stop doing any cheking of that file on platforms that are not windows. As far as I can see there are no other tests for this at the moment

[jenshnielsen]

Sorry that fails the docs build as it cannot import the code :(

The best workaround that I can come up with is to explicitly annotate self.dll as Any on Windows platforms.

I think the following will work (even if its a bit strange)

from typing import Dict, List, Optional, Tuple, Any

...

    def __init__(self, dll_path: Optional[str] = None, verbose: bool = False):
        if sys.platform != 'win32':
            self.dll: Any = None
            raise OSError("\"atmcd64d\" is only compatible with Microsoft Windows")
        else:
            self.verbose = verbose
            self.dll = ctypes.windll.LoadLibrary(dll_path or self._dll_path)

Edited to change from cdll to None with Any type

[lankes-fzj]

@jenshnielsen Thank you very much for your help :)