Changes 3: New Version class

[bastianallgeier]

This PR …

• 🚨 Merge first: Changes 1: Refactor content storage to use new VersionId class #6436
• 🚨 Merge first: Changes 2: Plain Text Handler Refactoring #6439

Refactoring

• New Version class which inherits most of the logic from the ContentStorage handler and will eventually replace it.

Outlook

• This PR will be followed by a later PR to improve the Version class and add additional unit tests (Changes 6: Version class improvements and unit tests #6450) The steps are separated to make sure that all other unit tests always keep passing. It's sometimes a bit of a chicken and egg situation here.
• Once the ContentStorageHandler methods accept a Language object instead of a string (Changes 4: Refactor PlainTextContentStorageHandler to use Language object #6448) the Version class also needs to pass a Language object instead of language codes. It will therefor get a new protected Version::language() method that is mostly adapted from ContentStorage::language() but will always return a Language object - even in a single-language installation. There's a new Language::single() method coming up in Changes 4: Refactor PlainTextContentStorageHandler to use Language object #6448 for that.
• The Version class will also inherit a few more specific logic methods from ContentStorage in preparation of removing ContentStorage entirely
  • ::deleteLanguage
  • ::touchLanguage
  • ::contentFile
• Version::modified will later return null if the version does not exist.
• Version::ensure will later use ContentStorageHandler::ensure Changes 10: New MemoryContentStorageHandler #6457

Breaking changes

None

Ready?

• In-code documentation (wherever needed)
• Unit tests for fixed bug/feature
• Tests and checks all pass

For review team

• Add changes & docs to release notes draft in Notion

[lukasbestle]

I assume Version will later cache the content object for each language, right?

[bastianallgeier]

Yes, exactly. But this isn't implemented in the other PRs so far. It's only on the todo list in Notion

[lukasbestle]

Added more context and links to our todo list for later. I agree it makes sense to merge this as is to avoid merge conflicts and endless rebasing. The class is not fully there yet, but we can and will improve it later in the process.

Added some comments on the tests. Same applies here: You don't have to change anything right now. I'd also be totally fine with merging the PR and adding those to the todo list for later.

[lukasbestle]

Makes sense. Could you add it to the todo list please?