RFE: Support external/custom version sources (plugins)

[jruzicka-nic]

After inspecting nvchecker source code I found no way to include custom version handlers without core code modification as they seem to be hardcoded into handlers_precedence list and loading is always done from nvchecker.source package.

Instead of forking/rewriting/reinventing the wheel, I'd prefer to extend nvchecker with a simple plugin system:

• put custom version sources into a predefined user directory (~/.nvchecker/sources ?) OR custom directory specified with new CLI argument (--extra-sources my_nv_sources_dir)
• load all valid extra source handlers and use them the very same way as those included in nvchecker.source

That way, users can:

• use nvchecker and its nice version handlers alongside custom handlers to get versions from all possible sources including those that aren't generic enough to have an upstream handler
• use/test custom handlers without forking nvchecker and optionally submit them easily for upstream inclusion

I'm willing and able to implement this if upstream is interested - please do let me know and I'll start hacking. Otherwise I'll be forced to create a competing project :)

[jruzicka-nic]

@lilydjwg you seem to be the benevolent ruler of this project - please let me what you think.

If this goes well, I'd love to contribute more to nvchecker over time as I always need such tool in my packaging adventures and your implementation is quite nice 👌

[lilydjwg]

A rewrite is ongoing to address several issues e.g. #132. Alongside those changes, I'm planning to use Python's native namespace packages for plugins.

Please wait for a few days for a test version of 2.0 to come out. This will be a breaking-changes version and target Python 3.7+.

[jruzicka-nic]

Awesome, I'm looking forward to test that hot new stuff ᕕ( ᐛ )ᕗ

[lilydjwg]

The new version (at branch nvchecker2) works now but only a small number of source modules are ported: https://github.com/lilydjwg/nvchecker/tree/nvchecker2/nvchecker_source. Two types of modules are supported, a simpler one for single-function cases and a class-based one for stuff like batch processing (see aur.py).

Documentation hasn't been updated yet.

[jruzicka-nic]

I briefly looked at nvchecker2 - it looks nice, I see you're not afraid to use latest python features :) But there are no docs or examples of howto use custom source yet (it's mentioned as TODO item in NEW file 👌) so I'm gonna wait for that before testing further.

Happy Hacking!

[lilydjwg]

The documentation is done!