Setting the file. One moment.
Chapter 02 · Expo Migrate Module
Subchapter 2.1
references/compatibility.mdMarkdown4 KBView on GitHub
The Expo Modules API 2.0 design and implementation evolve across the macros plugin and expo-modules-core. Verify the checked-out dependency instead of relying on an SDK-number claim.
Locate ExpoModulesMacros.swift in the target repository or installed dependencies (use your search tool, or portable shell commands - do not assume rg is installed):
find . -name 'ExpoModulesMacros.swift' -not -path '*/node_modules/.cache/*'Inspect the declarations that the user’s source can import:
grep -nE 'public macro (ExpoModule|JS|Event|SharedObject|Record|Union|ViewProps|ExpoView)' <path-to-ExpoModulesMacros.swift>A declaration proves only that Swift recognizes the attribute. Also inspect the corresponding macro implementation and core runtime hooks.
Search the actual core source for the feature being migrated:
grep -rnE '_decorateModule|_decorateSharedObject|_constructSharedObject|_jsName|EventEmitter|emitSync|StaticProperty|AnyViewProps|PropsDiff|_updateViewProps|didCreate|__expo_onStartListeningToEvent' <expo-modules-core>Use compile errors and symbol call sites to confirm signatures. The macros plugin and core can drift independently; a successful macro expansion does not prove the generated code compiles or is called at runtime.
Treat these as independent capabilities:
| Capability | Evidence required before migration |
|---|---|
| Module functions/properties | @ExpoModule/@JS, generated _decorateModule, and the core call site |
| Module name | generated _jsName and core registration/name lookup that reads it |
| Records | @Record, coding conformance/assertions, and field decode/encode support |
| Async events | @Event, EventEmitter, and BaseModule/SharedObject conformance |
| Shared-object instances | _decorateSharedObject, construction hook, and core invocation |
| Shared-object static functions | constructor object passed to decoration and static function routing |
| Synchronous events | @Event(sync:) plus core emitSync overloads |
| Task-returning functions | JavaScriptEncodable conformance for Task in core (encode-only) |
| Views | @ViewProps/@ExpoView plus the complete typed props update and event runtime |
| Module lifecycle methods | AnyModule requirements/base implementations and holder call sites |
If any required evidence is absent, keep that item in the 1.0 DSL.
Use this only as a warning list; checked-out source wins.
@JS overload grouping/dispatch was designed but not built; duplicate bindings could silently overwrite each other.@Union was not built.@ViewProps had only an initial pure-macro slice; the UIKit typed props runtime and @ExpoView contract were still gated on core.@Event(sync: true) macro generation existed, but core emitSync was still required.@Event was supported after core added EventEmitter to modules and shared objects.@JS functions/properties, range-based arity, default/optional-aware calls, @Record field synthesis, async @JavaScriptActor, and instance shared-object decoration had landed in the macros work.Use the target project’s own commands. A robust sequence is:
Do not report a migration complete based only on textual expansion tests.