feat: support late observables (#973)

Co-authored-by: Pavan Podila <pavanpodila@users.noreply.github.com>

mobx_codegen/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 2.5.0
+
+- Support `late` observables by [@amondnet](https://github.com/amondnet). fix [#919](https://github.com/mobxjs/mobx.dart/issues/919)
+
 ## 2.4.1
 
 - Adds `useDeepEquality` for creating observables by [@amondnet](https://github.com/amondnet)

mobx_codegen/lib/src/store_class_visitor.dart

@@ -102,6 +102,7 @@ class StoreClassVisitor extends SimpleElementVisitor {
  name: element.name,
  isPrivate: element.isPrivate,
  isReadOnly: _isObservableReadOnly(element),
+ isLate: element.isLate,
  equals: _getEquals(element),
  );
 

mobx_codegen/lib/src/template/observable.dart

@@ -11,6 +11,7 @@ class ObservableTemplate {
  required this.name,
  this.isReadOnly = false,
  this.isPrivate = false,
+ this.isLate = false,
  this.equals,
  this.useDeepEquality,
  });
@@ -21,6 +22,7 @@ class ObservableTemplate {
  final String name;
  final bool isPrivate;
  final bool isReadOnly;
+ final bool isLate;
  final ExecutableElement? equals;
  final bool? useDeepEquality;
 
@@ -53,16 +55,34 @@ class ObservableTemplate {
  }''';
  }
 
+ String _buildSetters() {
+ if (isLate) {
+ return '''
+ bool _${name}IsInitialized = false;
+ 
  @override
- String toString() => """
- late final $atomName = Atom(name: '${storeTemplate.parentTypeName}.$name', context: context);
-
-${_buildGetters()}
+ set $name($type value) {
+ $atomName.reportWrite(value, _${name}IsInitialized ? super.$name : null, () {
+ super.$name = value;
+ _${name}IsInitialized = true;
+ }${equals != null ? ', equals: ${equals!.name}' : ''});
+ }''';
+ }
 
+ return '''
  @override
  set $name($type value) {
  $atomName.reportWrite(value, super.$name, () {
  super.$name = value;
  }${equals != null ? ', equals: ${equals!.name}' : ''}${useDeepEquality != null ? ', useDeepEquality: $useDeepEquality' : ''});
- }""";
+ }''';
+ }
+
+ @override
+ String toString() => """
+ late final $atomName = Atom(name: '${storeTemplate.parentTypeName}.$name', context: context);
+
+${_buildGetters()}
+
+${_buildSetters()}""";
 }

mobx_codegen/lib/version.dart

@@ -1,4 +1,4 @@
 // Generated via set_version.dart. !!!DO NOT MODIFY BY HAND!!!
 
 /// The current version as per `pubspec.yaml`.
-const version = '2.4.1';
+const version = '2.5.0';

mobx_codegen/pubspec.yaml

@@ -1,6 +1,6 @@
 name: mobx_codegen
 description: Code generator for MobX that adds support for annotating your code with @observable, @computed, @action and also creating Store classes.
-version: 2.4.1
+version: 2.5.0
 
 homepage: https://github.com/mobxjs/mobx.dart
 issue_tracker: https://github.com/mobxjs/mobx.dart/issues

mobx_codegen/test/data/valid_late_variables_output.dart

@@ -8,10 +8,14 @@ mixin _$TestStore on _TestStore, Store {
  return super.username;
  }
 
+ bool _usernameIsInitialized = false;
+
  @override
  set username(String value) {
- _$usernameAtom.reportWrite(value, super.username, () {
+ _$usernameAtom
+ .reportWrite(value, _usernameIsInitialized ? super.username : null, () {
  super.username = value;
+ _usernameIsInitialized = true;
  });
  }
 }

mobx_codegen/test/generator_usage_test.dart

@@ -124,6 +124,9 @@ abstract class _TestStore with Store {
  // ignore: only_throw_errors
  throw 'TEST ERROR';
  }
+
+ @observable
+ late String lateField;
 }
 
 void main() {
@@ -279,4 +282,16 @@ void main() {
 
  expect(values, equals(['', 'field1', 'field2']));
  });
+
+ test('setting late fields with action works', () {
+ final store = TestStore('field1', field2: 'field2');
+
+ final fields = <String>[];
+ autorun((_) {
+ fields.add(store.lateField);
+ });
+ store.lateField = 'field';
+
+ expect(fields, equals(['field']));
+ });
 }