Resolve special stenzas lazily with no side-effects on the body

[nolar]

Resolve the special stenzas in the body lazily, on demand, without actual creation.

Issue : #194, #183

Description

There was an issue that spec, status, metadata fields were implicitly added to the body due to body.setdefault(..., {}) usage — even if such a stenzas didn't exist actually. From the users point of view, it appeared unexpectedly — i.e. an undesired side effect.

This was needed to ensure that the spec, status, metadata kwargs are exactly the same in the body kwarg, and any change in either of them is reflected in another one.

With this implementation, a dict-like object is introduced, which resolves these stenzas on-demand. In all other aspects, this object should behave like a normal dict.

In addition, this change is done as a preparation for the throughout type-hinting in the code base. Resolving the cyclic imports becomes important. The whole refactoring is split into few PRs (one per concept) for ease of review.

Types of Changes

• Bug fix (non-breaking change which fixes an issue)
• Refactor/improvements

Tasks

• Add proper repr()
• Check the behaviour when the dictview's field is received and remembered — does it match the expected behaviour.
• Check if Handlers receive empty dict for status when status is not set #183 is solved (patch generation in the assumption of no status stenza at all).

Review

• Tests
• Documentation

[zincr]

🤖 zincr found 0 problems , 0 warnings

✅ Large Commits
✅ Approvals
✅ Specification
✅ Dependency Licensing

[jonathanbeber]

+1