Make Plover HID not fail on startup

[user202729]

Summary of changes

From the documentation of hid (typo not mine):

pyhidapi is dependant upon the hidapi library, which must be installed separately.

This may not be installed, which means the import may raise ImportError.

For me, if that library is not installed, import hid fails with

ImportError: Unable to load any of the following libraries:libhidapi-hidraw.so libhidapi-hidraw.so.0 libhidapi-libusb.so libhidapi-libusb.so.0 libhidapi-iohidmanager.so libhidapi-iohidmanager.so.0 lib hidapi.dylib hidapi.dll libhidapi-0.dll

at startup. This change makes it so that it only fail when the user tries to select Plover HID as the input source.

Note: we don't actually need to depend on hid, that can be left as an optional dependency.

The from __future__ import annotations is just in case, because there are several type annotations that use hid.something, and on sufficiently-old Python versions they will actually be evaluated and raise errors (depends on what is the minimum-supported version this may not be necessary)

Note: only tested on Linux.

Note: I consider the case where the first import hid fails but the second succeed extremely unlikely, but it may look cleaner to capture the error message in the first import and log.error() it when started.

Pull Request Checklist

• Changes have tests
• News fragment added in news.d. See documentation for details

[mkrnr]

Thank you @user202729!

The current way of installing hidapi is indeed a pain and can result in the hid package missing.

I noticed, however, that hidapi 0.15.0 was recently released on PyPI. I did some tests and this version does fix the issue with macOS (hid_darwin_set_open_exclusive not being available) so I will try to migrate to that version next days. That would simplify our setup a lot and result in hid always being there.

If it's fine for you, let's park your PR in case I'm not successful with moving to that hidapi package.

[user202729]

#1812 fixes the issue on the machine I tested. Caveat is that the user must make sure that hid package is not also installed, otherwise the error remains. (probably plover can help with this by declaring conflicting package or something.)

That said, I don't understand how the linked pull request is supposed to fix the issue raised in this pull request. Quoting documentation of hidapi:

Software Dependencies

[...]

• hidraw or libusb+libudev on Linux

if the last entry is not installed, we would still get some sort of error?

I notice the dependency installs a hidraw.cpython-310-x86_64-linux-gnu.so file however.

[mkrnr]

Thanks @user202729 for testing with #1812. I assume you only checked if Plover works but not the Plover HID functionality itself? I'm asking because I'm having trouble getting the Plover HID keyboard to work on Linux. Windows and maCOS work perfectly.

[user202729]

Indeed, I don't need the functionality (currently I use the Keyboard machine with some local modifications to only activate on one keyboard but not another. I may upstream this feature eventually, but it's somewhat nontrivial…), only check that the error doesn't show up.