Following the discussion in #253 and #325 I've created a first iteration on what a `Backend` interface could look like and how the current file storage operations may be refactored into this interface. It goes from the following principles
* `app.py` talks only to `core.py` with regards to package operations
* at configuration time, a `Backend` implementation is chosen and created for the lifetime of the configured app
* `core.py` proxies requests for packages to this `Backend()`
* The `Backend` interface/api is defined through three things
* methods that an implementation must implement
* methods that an implementation may override if it knows better than the defaults
* the `PkgFIle` class that is (should be) the main carrier of data
* where possible, implementation details must be hidden from concrete `Backend`s to promote extensibility
Other things I've done in this PR:
* I've tried to talk about packages and projects, rather than files and prefixes, since these are the domain terms PEP503 uses, and imho it's also more clear what it means
* Better testability of the `CacheManager` (no more race conditions when `watchdog` is installed during testing)
* Cleanup some more Python 2 code
* Started moving away from `os.path` and `py.path` in favour of `pathlib`
Furthermore I've created a `plugin.py` with a sample of how I think plugin system could look like. This sampIe assumes we use `argparse` and allows for the extension of cli arguments that a plugin may need. I think the actual implementation of such a plugin system is beyond the scope of this PR, but I've used it as a target for the Backend refactoring. If requested, I'll remove it from this PR.
The following things still need to be done / discussed. These can be part of this PR or moved into their own, separate PRs
- [ ] Simplify the `PgkFile` class. It currently consists of a number of attributes that don't necessarily belong with it, and not all attributes are aptly named (imho). I would like to minimalize the scope of `PkgFile` so that its only concern is being a data carrier between the app and the backends, and make its use more clear.
- [ ] Add a `PkgFile.metadata` that backend implementations may use to store custom data for packages. For example the current `PkgFile.root` attribute is an implementation detail of the filestorage backends, and other Backend implementations should not be bothered by it.
- [ ] Use `pathlib` wherever possible. This may also result in less attributes for `PkgFile`, since some things may be just contained in a single `Path` object, instead of multtiple strings.
- [ ] Improve testing of the `CacheManager`.
----
* move some functions around in preparation for backend module
* rename pkg_utils to pkg_helpers to prevent confusion with stdlib pkgutil
* further implement the current filestorage as simple file backend
* rename prefix to project, since that's more descriptive
* add digester func as attribute to pkgfile
* WIP caching backend
* WIP make cache better testable
* better testability of cache
* WIP file backends as plugin
* fix typos, run black
* Apply suggestions from code review
Co-authored-by: Matthew Planchard <mplanchard@users.noreply.github.com>
* add more type hints to pass mypy, fix tox.ini
* add package count method to backend
* add package count method to backend
* minor changes
* bugfix when checking invalid whl file
* check for existing package recursively, bugfix, some more pathlib
* fix unittest
* rm dead code
* exclude bottle.py from coverage
* fix merge mistakes
* fix tab indentation
* backend as a cli argument
* fix cli, add tests
* fix mypy
* fix more silly mistakes
* process feedback
* remove dead code
Co-authored-by: Matthew Planchard <mplanchard@users.noreply.github.com>
