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jifalops/gist:8a59c7c8ae64daf6c02cd7ecca1aed0c

Forked from HansMuller/gist:b947e76c34d941397989eaab537d45ca
Created October 16, 2018 21:21
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Revisions

  1. jifalops renamed this gist Oct 16, 2018. 1 changed file with 0 additions and 0 deletions.
    0 gistfile1.txt → gistfile1.dart
    View file
    File renamed without changes.
  2. Hans Muller revised this gist Sep 6, 2018. 1 changed file with 5 additions and 0 deletions.
    5 changes: 5 additions & 0 deletions gistfile1.txt
    View file
    Original file line number Diff line number Diff line change
    @@ -13,6 +13,11 @@ class ABCModel extends InheritedModel<String> {
    final int b;
    final int c;

    @override
    bool updateShouldNotify(ABCModel old) {
    return a != old.a || b != old.b || c != old.c;
    }

    @override
    bool updateShouldNotifyDependent(ABCModel old, Set<String> fieldNames) {
    return (a != old.a && fieldNames.contains('a'))
  3. Hans Muller revised this gist Sep 6, 2018. 1 changed file with 4 additions and 4 deletions.
    8 changes: 4 additions & 4 deletions gistfile1.txt
    View file
    Original file line number Diff line number Diff line change
    @@ -14,10 +14,10 @@ class ABCModel extends InheritedModel<String> {
    final int c;

    @override
    bool updateShouldNotifyDependent(ABCModel old, Set<String> dependencies) {
    return (a != old.a && dependencies.contains('a'))
    || (b != old.b && dependencies.contains('b'))
    || (c != old.c && dependencies.contains('c'));
    bool updateShouldNotifyDependent(ABCModel old, Set<String> fieldNames) {
    return (a != old.a && fieldNames.contains('a'))
    || (b != old.b && fieldNames.contains('b'))
    || (c != old.c && fieldNames.contains('c'));
    }

    static ABCModel of(BuildContext context, { String fieldName }) {
  4. Hans Muller created this gist Aug 8, 2018.
    134 changes: 134 additions & 0 deletions gistfile1.txt
    View file
    Original file line number Diff line number Diff line change
    @@ -0,0 +1,134 @@
    import 'package:flutter/material.dart';

    class ABCModel extends InheritedModel<String> {
    ABCModel({
    Key key,
    this.a,
    this.b,
    this.c,
    Widget child,
    }) : super(key: key, child: child);

    final int a;
    final int b;
    final int c;

    @override
    bool updateShouldNotifyDependent(ABCModel old, Set<String> dependencies) {
    return (a != old.a && dependencies.contains('a'))
    || (b != old.b && dependencies.contains('b'))
    || (c != old.c && dependencies.contains('c'));
    }

    static ABCModel of(BuildContext context, { String fieldName }) {
    return InheritedModel.inheritFrom<ABCModel>(context, aspect: fieldName);
    }
    }

    class ShowABCField extends StatefulWidget {
    ShowABCField({ Key key, this.fieldName }) : super(key: key);

    final String fieldName;

    _ShowABCFieldState createState() => new _ShowABCFieldState();
    }

    class _ShowABCFieldState extends State<ShowABCField> {
    int _buildCount = 0;

    @override
    Widget build(BuildContext context) {
    final ABCModel abc = ABCModel.of(context, fieldName: widget.fieldName);
    final int value = widget.fieldName == 'a' ? abc.a : (widget.fieldName == 'b' ? abc.b : abc.c);
    return new Padding(
    padding: const EdgeInsets.symmetric(vertical: 8.0),
    child: new Text('${widget.fieldName} : $value [${_buildCount++}]', style: Theme.of(context).textTheme.title),
    );
    }
    }

    class ABCPage extends StatefulWidget {
    @override
    _ABCPageState createState() => new _ABCPageState();
    }

    class _ABCPageState extends State<ABCPage> {
    int _a = 0;
    int _b = 1;
    int _c = 2;

    @override
    Widget build(BuildContext context) {
    final Widget showA = new ShowABCField(fieldName: 'a');
    final Widget showB = new ShowABCField(fieldName: 'b');
    final Widget showC = new ShowABCField(fieldName: 'c');

    // Unconditionally depends on the ABCModel
    final Widget showABC = new Builder(
    builder: (BuildContext context) {
    final ABCModel abc = ABCModel.of(context);
    return new Text('a: ${abc.a} b: ${abc.b} c: ${abc.c}', style: Theme.of(context).textTheme.title);
    }
    );

    return new Scaffold(
    body: new StatefulBuilder(
    builder: (BuildContext context, StateSetter setState) {
    return new ABCModel(
    a: _a,
    b: _b,
    c: _c,
    child: new Center(
    child: new Column(
    mainAxisSize: MainAxisSize.min,
    children: <Widget>[
    showA,
    showB,
    showC,
    const SizedBox(height: 24.0),
    showABC,
    const SizedBox(height: 24.0),
    new RaisedButton(
    child: const Text('Increment a'),
    onPressed: () {
    // Rebuilds the ABCModel which triggers a rebuild
    // of showA because showA depends on the 'a' aspect
    // of the ABCModel.
    setState(() { _a += 1; });
    },
    ),
    new RaisedButton(
    child: const Text('Increment b'),
    onPressed: () {
    // Rebuilds the ABCModel which triggers a rebuild
    // of showB because showB depends on the 'b' aspect
    // of the ABCModel.
    setState(() { _b += 1; });
    },
    ),
    new RaisedButton(
    child: const Text('Increment c'),
    onPressed: () {
    // Rebuilds the ABCModel which triggers a rebuild
    // of showC because showC depends on the 'c' aspect
    // of the ABCModel.
    setState(() { _c += 1; });
    },
    ),
    ],
    ),
    ),
    );
    },
    ),
    );
    }
    }

    void main() {
    runApp(
    new MaterialApp(
    home: new ABCPage(),
    ),
    );
    }