feat: add experimental updateWith method on ValueWrapper

examples/hevy_smolov_jr/lib/steps/exercise_selection.dart

@@ -3,6 +3,7 @@ import 'package:flutter_rearch/flutter_rearch.dart';
 import 'package:fuzzywuzzy/fuzzywuzzy.dart';
 import 'package:hevy_smolov_jr/api/wrapped_hevy_api.dart';
 import 'package:hevy_smolov_jr/smolov_jr_config/config.dart';
+import 'package:rearch/experimental.dart';
 import 'package:rearch/rearch.dart';
 
 /// Displays the exercise selection step contents.
@@ -51,10 +52,9 @@ class _CuratedExercisePicker extends StatelessWidget {
             ChoiceChip(
               label: Text(exercise.title),
               selected: smolovJrConfig.value.exercise == exercise,
-              onSelected: (selected) {
-                smolovJrConfig.value =
-                    smolovJrConfig.value.copyWith(exercise: exercise);
-              },
+              onSelected: (selected) => smolovJrConfig.updateWith(
+                (config) => config.copyWith(exercise: exercise),
+              ),
             ),
         ],
       ),
@@ -103,8 +103,9 @@ class _AllExercisePicker extends RearchConsumer {
               subtitle: Text(exercise.primaryMuscleGroup.replaceAll('_', ' ')),
               onTap: () {
                 controller.closeView(exercise.title);
-                smolovJrConfig.value =
-                    smolovJrConfig.value.copyWith(exercise: exercise);
+                smolovJrConfig.updateWith(
+                  (config) => config.copyWith(exercise: exercise),
+                );
               },
             ),
         ];

examples/hevy_smolov_jr/lib/steps/program_config.dart

@@ -1,5 +1,6 @@
 import 'package:flutter/material.dart';
 import 'package:hevy_smolov_jr/smolov_jr_config/config.dart';
+import 'package:rearch/experimental.dart';
 import 'package:rearch/rearch.dart';
 
 /// Displays the program configuration step/
@@ -20,8 +21,9 @@ class ProgramConfigInputStep extends StatelessWidget {
               child: TextFormField(
                 keyboardType: TextInputType.number,
                 initialValue: smolovJrConfig.value.restSeconds.toString(),
-                onChanged: (s) => smolovJrConfig.value =
-                    smolovJrConfig.value.copyWith(restSeconds: int.tryParse(s)),
+                onChanged: (s) => smolovJrConfig.updateWith(
+                  (config) => config.copyWith(restSeconds: int.tryParse(s)),
+                ),
                 decoration: const InputDecoration(
                   hintText: 'rest',
                   suffixIcon: Text('seconds'),
@@ -40,8 +42,7 @@ class ProgramConfigInputStep extends StatelessWidget {
                 initialSelection: smolovJrConfig.value.unit,
                 onSelected: (unit) {
                   if (unit == null) return;
-                  smolovJrConfig.value =
-                      smolovJrConfig.value.copyWith(unit: unit);
+                  smolovJrConfig.updateWith((c) => c.copyWith(unit: unit));
                 },
                 dropdownMenuEntries: [
                   for (final unit in WeightUnit.values)
@@ -64,8 +65,9 @@ class ProgramConfigInputStep extends StatelessWidget {
                 keyboardType:
                     const TextInputType.numberWithOptions(decimal: true),
                 initialValue: smolovJrConfig.value.increment.toString(),
-                onChanged: (s) => smolovJrConfig.value =
-                    smolovJrConfig.value.copyWith(increment: num.parse(s)),
+                onChanged: (s) => smolovJrConfig.updateWith(
+                  (config) => config.copyWith(increment: num.parse(s)),
+                ),
                 decoration: InputDecoration(
                   hintText: 'weight',
                   suffixIcon: Text(smolovJrConfig.value.unit.name),
@@ -86,8 +88,9 @@ class ProgramConfigInputStep extends StatelessWidget {
                 keyboardType:
                     const TextInputType.numberWithOptions(decimal: true),
                 initialValue: smolovJrConfig.value.oneRepMax.toString(),
-                onChanged: (s) => smolovJrConfig.value =
-                    smolovJrConfig.value.copyWith(oneRepMax: num.parse(s)),
+                onChanged: (s) => smolovJrConfig.updateWith(
+                  (config) => config.copyWith(oneRepMax: num.parse(s)),
+                ),
                 decoration: InputDecoration(
                   hintText: 'weight',
                   suffixIcon: Text(smolovJrConfig.value.unit.name),
@@ -107,8 +110,9 @@ class ProgramConfigInputStep extends StatelessWidget {
                   keyboardType:
                       const TextInputType.numberWithOptions(decimal: true),
                   initialValue: smolovJrConfig.value.bodyWeight.toString(),
-                  onChanged: (s) => smolovJrConfig.value =
-                      smolovJrConfig.value.copyWith(bodyWeight: num.parse(s)),
+                  onChanged: (s) => smolovJrConfig.updateWith(
+                    (config) => config.copyWith(bodyWeight: num.parse(s)),
+                  ),
                   decoration: InputDecoration(
                     hintText: 'weight',
                     suffixIcon: Text(smolovJrConfig.value.unit.name),

packages/rearch/lib/experimental.dart

@@ -131,3 +131,19 @@ extension DynamicCapsuleCreationConvenience on CapsuleCreationConvenience {
     return (CapsuleHandle use) => use.dynamic(dyn);
   }
 }
+
+/// Provides [updateWith].
+extension ValueWrapperUpdateWith<T> on ValueWrapper<T> {
+  /// Updates the current [ValueWrapperProperty.value]
+  /// with the result of calling [mutater] on it.
+  ///
+  /// This can make it easier to update states using their `copyWith` methods:
+  /// ```dart
+  /// final myDataManager = capsule((use) => use.data(MyData()));
+  /// // ...
+  /// use(myDataManager).updateWith((data) => data.copyWith(foo: bar));
+  /// ```
+  /// NOTE: this is experimental because I think a future macro that generates a
+  /// dedicated `updateWith` for each type of `ValueWrapper<T>` could be nice.
+  void updateWith(T Function(T) mutater) => value = mutater(value);
+}