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Module Glossary

Page Maps

graph LR
  family["Python Programming"]
  program["Python Meta-Programming"]
  section["Descriptor Systems Validation Framework Design"]
  page["Module Glossary"]
  capstone["Capstone evidence"]

  family --> program --> section --> page
  page -.applies in.-> capstone
flowchart LR
  orient["Orient on the page map"] --> read["Read the main claim and examples"]
  read --> inspect["Inspect the related code, proof, or capstone surface"]
  inspect --> verify["Run or review the verification path"]
  verify --> apply["Apply the idea back to the module and capstone"]

This glossary belongs to Module 08: Descriptor Systems, Validation, and Framework Design in Python Metaprogramming. It keeps the language of this directory stable so the same ideas keep the same names across lessons, practice, review, and capstone discussion.

How to use this glossary

Use the glossary when framework-shaped descriptor discussions start to blur together cache policy, external sources of truth, wrapper fields, hint-driven validation, and broader architecture. Module 08 is meant to keep those boundaries explicit.

Use it for one more purpose as well:

to stop answers from sounding correct while staying ownership-vague. If a term cannot help you identify an owner, a source of truth, a refusal boundary, or an escalation rule, you are probably using it too loosely.

Use the glossary in both directions:

  • when you read a page, use it to decode what the design is actually claiming
  • when you write a review note, use it to catch words that sound informed but hide the real owner

Terms in this directory

Term Meaning in this directory
Cache invalidation The explicit act of clearing or refreshing a cached descriptor value when its dependencies or source data change.
Composed field A descriptor built by wrapping one field descriptor in another so an extra concern can be layered through delegation.
Descriptor-system packet A reviewable packet containing source-of-truth notes, invalidation rules, owner choices, rejected alternatives, and escalation boundaries for one descriptor design.
Evidence route A deliberate sequence of checks a learner uses to prove what a descriptor owns, where truth lives, and how failure or escalation is handled.
External source of truth The backing store outside the instance that ultimately owns a field's persisted value.
External-storage descriptor A descriptor that reads from or writes to backend-managed state rather than relying only on instance-local storage.
Field wrapper A delegating descriptor layer that adds one concern around an inner descriptor, such as validation or logging.
Framework boundary The point where descriptor behavior is no longer just per-field semantics and now requires explicit architectural owners.
Honest field claim A bounded description of what one field descriptor actually guarantees, without implying broader coordination it does not prove.
Hidden I/O The case where ordinary attribute access performs backend reads, writes, or serialization work that is not obvious from the syntax alone.
Hint-driven field A descriptor that reads annotations or Annotated[...] metadata as runtime evidence for validation or coercion.
Identity map A broader framework mechanism that keeps one in-memory object per record identity, explicitly outside the scope of a single descriptor.
Invalidation owner The code path, layer, or actor responsible for clearing cached state when it is no longer trustworthy.
Layer ledger A review note listing each wrapper layer, the one concern it owns, and the protocol path it must forward correctly.
Lower-power owner A smaller owner candidate that was considered but rejected because it cannot honestly carry the required contract.
Read-through cache A cache strategy where a descriptor fetches from the authoritative backend on miss, stores the value locally, and returns it.
Refusal surface The set of inputs, hint forms, behaviors, or architectural responsibilities a design intentionally declines to support.
Serialization boundary The conversion point between Python values and stored representations such as JSON strings.
Source of truth The location or system whose value should be treated as authoritative when field state and cached state diverge.
Stronger owner A broader owner candidate such as a service, session, repository, or framework layer that may be required when field scope is no longer enough.
Unit of work A wider framework pattern for coordinating multiple persistence changes together, beyond what one field descriptor should own.
Write-through behavior The strategy of persisting a new field value to the backend immediately when assignment occurs, while also updating local cached state.
Annotated[...] metadata Extra runtime metadata attached to a type annotation and often used here for validator-style field behavior.

Terms that must trigger a proof step

In this module, these words should never remain slogans.

If you use this term You must also prove...
source of truth which slot, store, or service wins when local and cached state disagree
invalidation owner what exact actor or code path clears stale state
field wrapper what one added concern the wrapper owns beyond the inner field
refusal surface which input, hint form, or broader responsibility is intentionally unsupported
stronger owner which wider coordination pressure forced escalation beyond one field
honest field claim which promise the descriptor can make now, and which larger promise it still refuses

Confusing pairs to keep separate

Pair Distinction to keep
computed access vs cached access computed recalculates; cached reuses and therefore needs freshness ownership
local storage vs external source of truth local storage may hold a copy; the external source still decides what is authoritative
composition vs subclass multiplication composition layers narrow concerns; subclass multiplication bakes combinations into a growing class tree
hint support vs runtime typing comprehensiveness a supported subset is honest; a vague claim of "runtime typing" is not
field ownership vs framework ownership one field can own attribute semantics; cross-record or lifecycle coordination needs broader architecture

Translation table for sloppy wording

Sloppy wording Stronger wording for this module
"the field stores it in the backend" "the field writes one serialized value to a named backend slot and may cache a local copy"
"the cache stays fresh" "the cache stays trustworthy only until its invalidation owner says otherwise"
"the wrappers add flexibility" "each wrapper adds one named concern around an inner field contract"
"the annotations define the model" "the field reads a named subset of hints and validator metadata at runtime"
"the descriptor is basically the framework" "the descriptor is one field-level mechanism inside a wider model or persistence architecture"

Review prompts for vocabulary

If a term appears in your notes, pressure-test it with one of these prompts:

  • who owns this?
  • where does truth live?
  • what does this design refuse?
  • what stronger owner would be needed if the blast radius grew?

If the term does not help answer one of those questions, tighten the wording.

Fast vocabulary drills

Use these when the module starts sounding familiar but still feels fuzzy:

Prompt Short answer shape to expect
what is the source of truth here? one exact slot, store, or authority
what can go stale here? one cache or mirrored state plus its invalidation owner
what does this wrapper add? one extra concern, not a vague improvement
what does the field refuse to support? one named unsupported hint, behavior, or architectural duty
when does this stop being one field? one concrete escalation trigger and broader owner

Keep the module connected