Upgrade to Pro
— share decks privately, control downloads, hide ads and more …
Speaker Deck
Speaker Deck
PRO
Sign in
Sign up for free
Flutter Hooks を使ったアプリ開発 / App Development with the Flutter Hooks
Daichi Furiya (Wasabeef)
March 23, 2022
Programming
2
810
Flutter Hooks を使ったアプリ開発 / App Development with the Flutter Hooks
CyberAgent Developer Conference 2022
Daichi Furiya (Wasabeef)
March 23, 2022
Tweet
Share
More Decks by Daichi Furiya (Wasabeef)
See All by Daichi Furiya (Wasabeef)
DevFest_2022_What_it_Takes_to_be_a_Flutter_Developer
wasabeef
0
12
FlutterKaigi 2022 Keynote
wasabeef
1
330
Flutter 2021 の振り返りと今後のアプリ開発に向けて / Looking back on Flutter 2021 and for future app development.
wasabeef
4
1.8k
Flutter Hooks, sometimes Jetpack Compose
wasabeef
2
1.4k
Skia and Skija, Skiko [ja]
wasabeef
1
1.2k
Flutter はプロダクション開発に耐えうるのか / Flutter ready for production?
wasabeef
34
11k
モバイル開発におけるクロスプラットフォームの期待と課題 / Cross-platform expectations and challenges in mobile development
wasabeef
0
290
Repository with Store4 [ja]
wasabeef
2
1.1k
来年に備えるために Android の知識を網羅する / Looking back on this Android year in preparation for next year.
wasabeef
17
13k
Other Decks in Programming
See All in Programming
量子コンピュータ時代のプログラミングセミナー / 20221222_Amplify_seminar _route_optimization
fixstars
0
250
新卒でサービス立ち上げから Hasuraを使って3年経った振り返り
yutorin
0
240
ペパカレで入社した私が感じた2つのギャップと向き合い方
kosuke_ito
0
320
Unity+C#で学ぶ! メモリレイアウトとvtableのすゝめ 〜動的ポリモーフィズムを実現する仕組み〜
rossam
1
360
はじめての「R」
masaha03
0
100
Listかもしれない
irof
1
280
Gradle build: The time is now
nonews
1
500
42tokyo-born2beroot-review
love42
0
120
爆速の日経電子版開発の今
shinyaigeek
2
660
Writing Greener Java Applications
hollycummins
0
360
Qiita Night PHP 2023
fuwasegu
0
11k
Azure Functionsをサクッと開発、サクッとデプロイ/vscodeconf2023-baba
nina01
1
350
Featured
See All Featured
Optimizing for Happiness
mojombo
365
64k
実際に使うSQLの書き方 徹底解説 / pgcon21j-tutorial
soudai
44
14k
CoffeeScript is Beautiful & I Never Want to Write Plain JavaScript Again
sstephenson
152
13k
Faster Mobile Websites
deanohume
295
29k
Art Directing for the Web. Five minutes with CSS Template Areas
malarkey
197
10k
Responsive Adventures: Dirty Tricks From The Dark Corners of Front-End
smashingmag
239
19k
YesSQL, Process and Tooling at Scale
rocio
159
12k
Scaling GitHub
holman
453
140k
The Illustrated Children's Guide to Kubernetes
chrisshort
22
43k
RailsConf & Balkan Ruby 2019: The Past, Present, and Future of Rails at GitHub
eileencodes
120
29k
Code Review Best Practice
trishagee
50
11k
Thoughts on Productivity
jonyablonski
49
2.7k
Transcript
None
߱େ גࣜձࣾαΠόʔΤʔδΣϯτ ϝσΟΞ౷ׅຊ෦ %FWFMPQFS1SPEVDUJWJUZࣨ
[email protected]
XBTBCFFG (PPHMF%FWFMPQFST&YQFSU
"HFOEB wαΠόʔΤʔδΣϯτͷ'MVUUFS࠾༻ࣄྫ w'MVUUFS)PPLTΛͬͨΞϓϦ։ൃ w 'MVUUFS)PPLTͱʁ w 4UBUFGVM8JEHFUͷϥΠϑαΠΫϧΛར༻ͨ͠߹ w 'MVUUFS)PPLTΛجຊΛཧղ͢Δ w
'MVUUFS)PPLTͷޮՌతͳར༻๏ wࠓޙͷల
αΠόʔΤʔδΣϯτͷ'MVUUFS࠾༻ࣄྫ
'MVUUFSͷ࠾༻ࣄྫ ग़యɿIUUQTXXXDZCFSBHFOUDPKQUFDIJOGPJOGPEFUBJMJE
'MVUUFS)PPLTΛͬͨΞϓϦ։ൃ
'MVUUFS)PPLTͱʁ
'MVUUFS)PPLTͱʁ ग़యɿIUUQTHJUIVCDPNSSPVTTFM(JU fl
[email protected]
ग़యɿIUUQTSFBDUKTPSHEPDTIPPLTJOUSPIUNM w 3FBDU)PPLTͷ'MVUUFS൛Ͱจ๏͍ํ΄΅ಉ͡ͷ
4UBUFGVM8JEHFUͷ ϥΠϑαΠΫϧΛ ར༻ͨ͠߹
class CountPage extends StatefulWidget { @override State createState() => _CountState();
} class _CountState extends State<CountPage> { int count = 0; @override void initState() { / ** ॳظԽ **/ } @override void dispose() { /** ഁغ **/ } void setCount(int value) => setState(() = > count = value); @override Widget build(BuildContext context) { return TextButton( child: Text("Count is $count"), onPressed: () => setCount(count + 1), ); } } w γεςϜͷঢ়ଶͳͲʹΑͬͯಈతʹ มԽΛ͢Δখ͞ͳϥΠϑαΠΫϧΛ ͬͨΟδΣοτ w *NBHFɺ5FYU'PSN'JFME)FSPͳ Ͳ͕4UBUFGVM8JEHFUͷαϒΫϥε 4UBUFGVM8JEHFUͷઆ໌
class CountPage extends StatefulWidget { @override State createState() => _CountState();
} class _CountState extends State<CountPage> { int count = 0; @override void initState() { / ** ॳظԽ **/ } @override void dispose() { /** ഁغ **/ } void setCount(int value) => setState(() = > count = value); @override Widget build(BuildContext context) { return TextButton( child: Text("Count is $count"), onPressed: () => setCount(count + 1), ); } } 4UBUFGVM8JEHFUΛ͏ʹجຊతʹೋͭͷ ΫϥεΛ࡞Δඞཁ͕͋Δ w 4UBUFGVM8JEHFUΛܧঝͨ͠$PVOU1BHF w 4UBUF5Λܧঝͨ͠@$PVOU4UBUF 4UBUFGVM8JEHFUͷઆ໌
class CountPage extends StatefulWidget { @override State createState() => _CountState();
} class _CountState extends State<CountPage> { int count = 0; @override void initState() { / ** ॳظԽ **/ } @override void dispose() { /** ഁغ **/ } void setCount(int value) => setState(() = > count = value); @override Widget build(BuildContext context) { return TextButton( child: Text("Count is $count"), onPressed: () => setCount(count + 1), ); } } 4UBUFGVM8JEHFUͷઆ໌ 4UBUFGVM8JEHFUΛ͏ʹجຊతʹೋͭͷ ΫϥεΛ࡞Δඞཁ͕͋Δ w 4UBUFGVM8JEHFUΛܧঝͨ͠$PVOU1BHF w 4UBUF5Λܧঝͨ͠@$PVOU4UBUF
class CountPage extends StatefulWidget { @override State createState() => _CountState();
} class _CountState extends State<CountPage> { int count = 0; @override void initState() { / ** ॳظԽ **/ } @override void dispose() { /** ഁغ **/ } void setCount(int value) => setState(() = > count = value); @override Widget build(BuildContext context) { return TextButton( child: Text("Count is $count"), onPressed: () => setCount(count + 1), ); } } 4UBUFGVM8JEHFUͷઆ໌ JOJU4UBUFɿॳظԽͷॲཧ EJTQPTFɿഁغͷॲཧ TFU4UBUFɿݺͿ͜ͱͰঢ়ଶ͕มԽͨ͜͠ͱ Λ௨ͯ͠ϦϏϧυ͕Δ
4UBUFGVM8JEHFUͰ࣮ͨ͠߹ͷ՝ w ঢ়ଶΛอ࣋͢ΔΫϥεΛ৽ͨʹ࡞Βͳ͍ͱ͍͚ͳ͍ w ෳࡶͳϩδοΫΛؚΉঢ়ଶΛอ͍࣋ͨ͠߹ʹϩδοΫ ͱΟδΣοτΛͰ͖͍ͯͳ͍ w ίʔυͷ࠶ར༻͕ѱ͍ w ςετ͕ॻ͖ʹ͍͘
'MVUUFS)PPLTͷ جຊΛཧղ͢Δ
'MVUUFS)PPLTͰԿ͕ղܾͰ͖Δ͔ ग़యɿIUUQTHJUIVCDPNSSPVTTFM(JU fl
[email protected]
ग़యɿIUUQTSFBDUKTPSHEPDTIPPLTJOUSPIUNM w એݴత6*ͰΫϥΠΞϯτΛ্࣮͍ͯ͘͠ͰɺϩδοΫͱ ΟδΣοτʢίϯϙʔωϯτʣͷΛϝϯςφϯεੑΛอ ͪͭͭҡ࣋͢Δͷ͕͘͠ɺͦΕΛղܾ͢ΔػೳΛఏڙ͢Δ w
ίϯϙʔωϯτΛͪΌΜͱؔͱͯ͠ѻ͏ͨΊ w ΫϥεͷఆٛΛݮΒ͢ʢγϯλοΫεγϡΨʔʣͨΊ w 'MVUUFSͷΟδΣοτසൟʹ࠶ඳը͕࣮ߦ͞ΕΔͨΊॏ͍ ԋࢉෳࡶͳॲཧΛ͚͞ΕΔΑ͏ͳػೳΛఏڙ͢Δ w ಉ͡ೖྗσʔλͷ߹ʹ݁ՌΛΩϟογϡ͢Δ
VTF4UBUFΛཧղ͢Δ VTF4UBUF'MVUUFS)PPLTΛར༻͢ΔͳΒඞͣར༻͢Δ Ͱ͋Ζ͏جຊతͳϑοΫͰ͢ʢ෦࣮7BMVF/PUJGJFSʣ ར༻͢Δʹ֮͋ͨͬͯ͑Δ͜ͱ؆୯ͰVTF4UBUF 5 Ͱॳظ Λ༩͑ɺDPVOUWBMVFͷΛมߋ͢Δ͜ͱͰ࠶ඳը // ॳظԽ final
count = useState(0); // ͷߋ৽Λ࠶ඳը count.value = 3;
VTF4UBUFΛཧղ͢Δ ঢ়ଶͷཧΛ͢ΔͨΊʹϞόΠϧΞϓϦ։ൃͷΞʔΩςΫ νϟͰΑ͘ฉ͘Α͏ͳ7JFX.PEFM4UPSFΛ༻ҙ͢Δ΄ ͲͰͳ͍߹ʹར༻͢Δ͜ͱͰ͖Δ ྫ͑ɺϘλϯͷ&OBCMFE%JTBCMFEͷঢ়ଶͷอ࣋Θ͟ Θ͟ΫϥεΛ࡞Δ·Ͱͳ͘ɺͦͷΟδΣοτͰอ࣋͢ ΔͳͲ
VTF4UBUFΛཧղ͢Δ class CountPage extends HookWidget { @override Widget build(BuildContext context)
{ final count = useState(0); return TextButton( onPressed: () { count.value ++ ; }, child: Text("Count is ${count.value}"), ); } } class CountPage extends StatefulWidget { @override State createState() => _CountState(); } class _CountState extends State<CountPage> { int count = 0; void setCount(int value) => setState(() = > count = value); @override Widget build(BuildContext context) { return TextButton( child: Text("Count is $count"), onPressed: () => setCount(count + 1), ); } } 4UBUFGVM8JEHFU VTF4UBUF େ͖ͳҧ͍4UBUFΛܧঝͨ͠Ϋϥε͕ඞ ཁͩͬͨͷ͕ͳ͘ͳΓVTF4UBUF 5 ʹॳ ظΛ༩͑Δ͚ͩʹͳ͍ͬͯΔ
VTF4UBUFΛཧղ͢Δ class CountPage extends HookWidget { @override Widget build(BuildContext context)
{ final count = useState(0); return TextButton( onPressed: () { count.value + + ; }, child: Text("Count is ${count.value}"), ); } }
VTF& ff FDUΛཧղ͢Δ ؆୯ͳΟδΣοτͷϥΠϑαΠΫϧͰॲཧ͕ඞཁͩͬͨ ߹ʹVTF&GGFDUΛ͏ ʢΟδΣοτੜ࣌ʹॳظԽഁغΛ͍ͨ͠߹ͳͲʣ class _CountState extends
State<CountPage> { ɹ // . .. @override void initState() { / ** ॳظԽ **/ } @override void dispose() { /** ഁغ **/ } } ɹ // . .. } 4UBUFGVM8JEHFUͷJOJU4UBUFEJQPTF૬
VTF& ff FDUΛཧղ͢Δ class CountPage extends HookWidget { @override Widget
build(BuildContext context) { useEffect(() => { / / ॳظԽ final subscription = source.subscribe(id); return () => { // ഁغ subscription.unsubscribe(id); }; }, [id]); return // Widget . .. } } 8JEHFUͷCVJMEͰVTF&GGFDUͷୈҰҾ ʹΫϩʔδϟΛ͠ɺͦͷΫϩʔδϟͷ SFUVSO࣌ʹഁغ࣌ͷॲཧΛॻ͘ VTF&GGFDUͷୈೋҾʹॳظԽΛϏϧυ࣌ ʹຖճ࣮ߦ͞Εͳ͍Α͏ʹΩʔͱͳΔΦϒ δΣΫτΛ͢ඞཁ͕͋Δ
VTF& ff FDUͷୈೋҾॏཁ class CountPage extends HookWidget { @override Widget
build(BuildContext context) { useEffect(() => { / / ᶃ ID ͕มߋ͞ΕΔͨͼʹݺͼग़͠ }, [id]); useEffect(() => { / / ᶄ ຖճݺͼग़͠ }); useEffect(() => { / / ᶅ ࠷ॳͷҰճ͚ͩݺͼग़͠ }, const []); return // Widget . .. } }
VTF"OJNBUJPO$POUSPMMFSΛར༻ͯ͠ΈΔ class Example extends StatefulWidget { final Duration duration; const
Example({Key? key, required this.duration}) : super(key: key); @override _ExampleState createState() => _ExampleState(); } class _ExampleState extends State<Example> with SingleTickerProviderStateMixin { AnimationController? _controller; @override void initState() { super.initState(); _controller = AnimationController(vsync: this, duration: widget.duration); } @override void didUpdateWidget(Example oldWidget) { super.didUpdateWidget(oldWidget); if (widget.duration != oldWidget.duration) { _controller!.duration = widget.duration; } } @override void dispose() { _controller!.dispose(); super.dispose(); } @override Widget build(BuildContext context) { return Container(); } } 4UBUFGVM8JEHFU 'MVUUFSͰΞχϝʔγϣϯΛ4UBUFGVM8JEHFU Ͱ࣮͠Α͏ͱ͢Δͱঢ়ଶཧͷίʔυΛΫ ϥεʹ͚ͩͰ͜Ε͚ͩඞཁʹͳΓͦͷଟ͕͘ ͍ճ͠Ͱ͖ͳ͍ίʔυʹͳΔ ˞ͳίʔυΛݮΒ͢ͱ͍͏త͚ͩͰ͋ Ε%BSUʹ.JYJO͕͋ΔͷͰͦΕͰڞ௨ Խ͢Δ͜ͱͰ͖Δ
VTF"OJNBUJPO$POUSPMMFSΛར༻ͯ͠ΈΔ class Example extends HookWidget { const Example({required this.duration}); final
Duration duration; @override Widget build(BuildContext context) { final controller = useAnimationController(duration: duration); return Container(); } } class Example extends StatefulWidget { final Duration duration; const Example({Key? key, required this.duration}) : super(key: key); @override _ExampleState createState() => _ExampleState(); } class _ExampleState extends State<Example> with SingleTickerProviderStateMixin { AnimationController? _controller; @override void initState() { super.initState(); _controller = AnimationController(vsync: this, duration: widget.duration); } @override void didUpdateWidget(Example oldWidget) { super.didUpdateWidget(oldWidget); if (widget.duration != oldWidget.duration) { _controller!.duration = widget.duration; } } @override void dispose() { _controller!.dispose(); super.dispose(); } @override Widget build(BuildContext context) { return Container(); } } 4UBUFGVM8JEHFU VTF"OJNBUJPO$POUSPMMFS VTF"OJNBUJPO$POUSPMMFSΛ͏͜ͱͰ ͳίʔυྔݮΒ͢͜ͱ͕Ͱ͖ɺར༻ଆͰͷ ίετΛԼ͛Δ͜ͱ͕Ͱ͖Δ
'MVUUFS)PPLTͷ ޮՌతͳར༻๏
ΧελϜϑοΫΛ࡞͢Δ w ໊ؔʹVTF999ͱ͍͏໊લΛ͚ͭΔ w ࠷ॳVTF4UBUFVTF& ff FDUΛΈ߹Θ ࣮ͤͯͯ͠ΈΔ VoidCallback useUpdate()
{ final attempt = useState(0); return () => attempt.value ++ ; } class Sample extends HookWidget { @override Widget build(BuildContext context) { final update = useUpdate(); return Column( children: [ ElevatedButton( onPressed: () => update(), child: const Text("Update"), ), ] ); } } VTF6QEBUF 4BNQMF
fl
[email protected]
ϥΠϒϥϦΛར༻ͯ͠ΈΔ w
[email protected]
ͷ'MVUUFS൛ w Λ͑Δ৭ʑͳϢʔεέʔεʹରԠͨ͠ΧελϜϑοΫू w ࣗ࡞ΧελϜϑοΫΛ࡞Δͱ͖ʹࢀߟʹͰ͖Δʢͱࢥ͏ʣ
fl
[email protected]
ϥΠϒϥϦΛར༻ͯ͠ΈΔ
VTF& ff FDU0ODFΛར༻ͯ͠ΈΔ w fl
[email protected]
ʹ͓͍ͯ࠷୯७ͳ࣮ w VTF& ff FDUͷୈೋҾΛলུ͢ΔͨΊͷΧελϜϑοΫ
useEffect(() => { // ࠷ॳͷҰճ͚ͩݺͼग़͠ }, const []); void useEffectOnce(Dispose? Function() effect) { return useEffect(effect, const []); } VTF&GGFDU VTF&GGFDU0ODFͷ࣮
VTF& ff FDU0ODFΛར༻ͯ͠ΈΔ w fl
[email protected]
ʹ͓͍ͯ࠷୯७ͳ࣮ w VTF& ff FDUͷୈೋҾΛলུ͢ΔͨΊͷΧελϜϑοΫ
useEffect(() => { // ࠷ॳͷҰճ͚ͩݺͼग़͠ }, const []); void useEffectOnce(Dispose? Function() effect) { return useEffect(effect, const []); } VTF&GGFDU VTF&GGFDU0ODFͷ࣮
w ΞϓϦཁ݅ͰԿඵޙʹॲཧΛ࣮ߦ͍ͤͨ͞߹ w VTF5JNFPVUVTF5JNFPVU'OΛ͏͜ͱͰࢦఆͷ࣌ؒܦա ޙʹϦϏϧυΫϩʔδϟΛ࣮ߦ͢Δ͜ͱ͕Ͱ͖Δ class Sample extends HookWidget {
@override Widget build(BuildContext context) { final timeout = useTimeout(const Duration(seconds: 3)); return Column( children: [ Text("isReady ?: ${timeout.isReady}"), ElevatedButton( onPressed: () => timeout.reset(), child: const Text("Reset"), ), ], ); } } VTF5JNFPVUΛར༻ͯ͠ΈΔ
w ෦Ͱ
[email protected]
ͱ͍͏ϥΠϒϥϦΛͬͯ ͷωοτϫʔΫঢ়گΛऔಘ͍ͯ͠Δ w ࣗͰ࣮͢Δͱඇಉظॲཧͷ੍ޚͳͲ͕ඞཁ͕ͩɺ͜ ͷΧελϜϑοΫͰར༻ଆγϯϓϧʹ͍ͯ͠Δ class Sample extends HookWidget
{ @override Widget build(BuildContext context) { final networkState = useNetworkState(); return Column( children: [ Text( "Network: ${networkState.connectivityResult}"), ], ); } } VTF/FUXPSL4UBUFΛར༻ͯ͠ΈΔ
fl
[email protected]
IUUQTHJUIVCDPNXBTBCFFG fl
[email protected]
ΧελϜϑοΫͷςετ w 'MVUUFS)PPLT5FTUJOH-JCSBSZΛར༻ͯ͠ΈΔ w SFBDUIPPLTUFTUJOHMJCSBSZͷ'MVUUFS൛
ϥΠϒϥϦΛར༻͠ͳ͍߹ testWidgets('usePrevious', (tester) async { await tester.pumpWidget( HookBuilder(builder: (context) {
usePrevious(42); return const SizedBox(); }), ); await tester.pumpWidget( HookBuilder(builder: (context) { usePrevious(21); return const SizedBox(); }), ); final element = tester.element(find.byType(HookBuilder)); expect( element .toDiagnosticsNode(style: DiagnosticsTreeStyle.offstage) .toStringDeep(), equalsIgnoringHashCodes( 'HookBuilder\n' ' │ usePrevious: 42\n' ' └SizedBox(renderObject: RenderConstrainedBox#00000)\n', ), ); }); VTF1SFWJPVT'MVUUFS)PPLTʹඪ ४Ͱؚ·Ε͍ͯΔ༩͑ͨͷҰͭલͷ ঢ়ଶΛอ࣋͢ΔΧελϜϑοΫ ͜ͷϑοΫΛςετॻ͘߹ʹ࠷ Ͱ͜Ε͚ͩͷίʔυྔͰ͢
testWidgets('usePrevious', (tester) async { / / ... await tester.pumpWidget( HookBuilder(builder:
(context) { usePrevious(42); return const SizedBox(); }), ); / / ... }); ϥΠϒϥϦΛར༻͠ͳ͍߹ গ͠ࡉ͔͘આ໌͍ͯ͘͠ͱɺ QVNQ8JEHFUͱ͍͏ςετ༻Ο δΣοτͷঢ়ଶΛཧ͍ͯ͠Δؔʹ )PPL#VJMEFSΛͯ͠ɺͦͷதͰΧε λϜϑοΫΛ͏ඞཁ͕͋Δ
testWidgets('usePrevious', (tester) async { / / ... await tester.pumpWidget( HookBuilder(builder:
(context) { usePrevious(21); return const SizedBox(); }), ); / / ... }); ϥΠϒϥϦΛར༻͠ͳ͍߹ ͏Ұߋ৽͠ͳ͍ͱ͍͚ͳ͍ͷͰɺ ઌ΄Ͳ͕ͩͬͨࠓճΛ ͍ͯ͠Δ
testWidgets('usePrevious', (tester) async { // .. . final element =
tester.element(find.byType(HookBuilder)); expect( element .toDiagnosticsNode(style: DiagnosticsTreeStyle.offstage) .toStringDeep(), equalsIgnoringHashCodes( 'HookBuilder\n' ' │ usePrevious: 42\n' ' └SizedBox(renderObject: RenderConstrainedBox#00000)\n', ), ); // .. . }); VTF1SFWJPVTͱ͍͏ҰͭલͷΛอ࣋ ͢ΔͷͰ࠷ॳʹ͕ͨ͠ݱࡏอ࣋ ͍ͯ͠ΔͱͳΔ ͜ΕΛνΣοΫ͢ΔͨΊʹςετΟ δΣοτͷϊʔυΛจࣈྻ͔Βϋο γϡίʔυͰൺֱ͍ͯ͠Δ ϥΠϒϥϦΛར༻͠ͳ͍߹
testWidgets('usePrevious', (tester) async { await tester.pumpWidget( HookBuilder(builder: (context) { usePrevious(42);
return const SizedBox(); }), ); await tester.pumpWidget( HookBuilder(builder: (context) { usePrevious(21); return const SizedBox(); }), ); final element = tester.element(find.byType(HookBuilder)); expect( element .toDiagnosticsNode(style: DiagnosticsTreeStyle.offstage) .toStringDeep(), equalsIgnoringHashCodes( 'HookBuilder\n' ' │ usePrevious: 42\n' ' └SizedBox(renderObject: RenderConstrainedBox#00000)\n', ), ); }); ϥΠϒϥϦΛར༻͠ͳ͍߹
testWidgets('usePrevious', (tester) async { final result = await buildHook( (value)
= > usePrevious(value), initialProps: 42, ); await result.rebuild(21); expect(result.current, 42); }); testWidgets('usePrevious', (tester) async { await tester.pumpWidget( HookBuilder(builder: (context) { usePrevious(42); return const SizedBox(); }), ); await tester.pumpWidget( HookBuilder(builder: (context) { usePrevious(21); return const SizedBox(); }), ); final element = tester.element(find.byType(HookBuilder)); expect( element .toDiagnosticsNode(style: DiagnosticsTreeStyle.offstage) .toStringDeep(), equalsIgnoringHashCodes( 'HookBuilder\n' ' │ usePrevious: 42\n' ' └SizedBox(renderObject: RenderConstrainedBox#00000)\n', ), ); }); ར༻͠ͳ͍ ར༻͢Δ ΧελϜϑοΫͷঢ়ଶΛߋ৽͢ΔͨΊʹ UFTUFSQVNQ8JEHFUʹ)PPL#VJMEFSΛຖ ճ͍ͯͨ͠ͷΛলུͰ͖ɺFYQFDU࣌ͷ ঢ়ଶऔಘγϯϓϧʹॻ͚Δ ϥΠϒϥϦΛར༻͢Δ߹
testWidgets('usePrevious', (tester) async { final result = await buildHook( (value)
= > usePrevious(value), initialProps: 42, ); await result.rebuild(21); expect(result.current, 42); }); 'MVUUFS)PPLT5FTUJOH-JCSBSZΛར༻ͨ͠ ߹ଟ͘ͷίʔυΛݮ͢Δ͜ͱ͕Ͱ͖Δ CVJME)PPLɿͷΫϩʔδϟʹΧελϜϑοΫͷ ݺͼग़͠Λॻ͖ɺୈೋҾʹॳظΛ༩͑Δ͜ ͱ͕Ͱ͖Δ SFCVJMEɿCVJME)PPLͰੜ͞ΕͨΫϥεͰ Λߋ৽͠ϦϏϧυͰ͖Δ DVSSFOUɿอ͍࣋ͯ͠ΔΛऔಘͰ͖Δ ϥΠϒϥϦΛར༻͢Δ߹
'MVUUFS)PPLT5FTUJOH-JCSBSZ IUUQTHJUIVCDPNXBTBCFFG fl
[email protected]
@UFTU
'MVUUFS)PPLTͷ-JOU w fl
[email protected]
@
[email protected]
Λར༻ͯ͠ΈΔ w FTMJOUQMVHJOSFBDUIPPLTͷ'MVUUFS൛ IUUQTHJUIVCDPNNKIE fl
[email protected]
@
[email protected]
final variable1 = callSomething(); final variable2 = callSomething(); // ෆඞཁ·ͨෆ͍ͯ͠ΔΩʔ
useEffect(() { print(variable1); }, [variable2]); // ϑοΫΛ݅ذͷதʹೖΕͳ͍ if (flag) { final variable = useState('hello'); } ϑοΫʹ͍͔ͭ͘ͷϧʔϧ͕͋Γ·͢ ྫ w ΧελϜϑοΫͷ໊ؔʹVTF999 ͱ͍͏໊લΛ͚ͭΔ ɾϑοΫΛ݅ذʹೖΕͳ͍ ͜ͷ1MVHJOΛ͏͜ͱͰόάΛ͙ͱڞ ʹϨϏϡʔͷίετͳͲͷԼ͛Δ fl
[email protected]
@
[email protected]
Λར༻ͯ͠ΈΔ
ࠓޙͷల
ࠓޙͷల w )PPLTʹΑΔੈք؍Λ'MVUUFSք۾ʹਁಁ͍͖͍ͤͯͨ͞ w ੵۃతʹ'MVUUFSΑΓྺ࢙ͷ͋Δ3FBDU͔ΒऔΓೖΕ͍ͯ͘ w ྺ࢙3FBDUʼ'MVUUFSʼ+FUQBDL$PNQPTF4XJGU6*ͳͷͰ 'MVUUFSͷݟΛ+FUQBDL$PNQPTFͳͲʹస༻͍ͯ͘͠ w 3FBDU2VFSZʹΑΔγϯϓϧͳઃܭΛ'MVUUFSʹऔΓೖΕ͍ͨ
w ΞϓϦΞʔΩςΫνϟʹ࣌ؒΛ͔͚ͳ͍ੈք؍ͷ044࡞Δ w 3FDPJMɺ.77.ͳͲͷֶशʹ࣌ؒΛΘͣ؆୯ͳΞϓϦΛ؆୯ʹ࡞Δ ग़యɿIUUQTXXXJSBTVUPZBDPN