facebookarchive/prepack

Review/enforce possible values / types of tracked object properties

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#1,124 opened on Nov 1, 2017

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bootcampeddesign neededhelp wantedlevel 3 (medium)test needed

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Description

In ObjectValue.js, there's a list of trackedPropertyNames.

Tracked objects must be void or a (subtype of a) Value. After state joins, an AbstractValue may appear (encoding a conditional expression), or possibly other Value kinds due to simplification rules. Maybe there's some special logic in place for arrays (otherwise, how does $MapData and $SetData and $WeakMapData and $WeakSetData work as tracked objects?)

We should...

  • Document the actual requirements where trackedPropertyNames is defined
  • Consider including type information in trackedPropertyNames and issuing type invariant checks as part of the property injection in setupTrackedPropertyAccessors.
  • Manually review all static Flow types of tracked properties to check if they conform

Contributor guide

Research direction
Investigate the trackedPropertyNames list in ObjectValue.js, document the types and constraints, and manually verify each tracked property's static Flow type.
Tech stack
javascript
Domain
backend
Issue type
Documentation
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-2 days
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Needs investigation
Prerequisites
JavaScriptFlow
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
35