This pull request aims to improve code readability, based on feedback gathered in a recent design doc.
<br>
There are two factors that hugely impact how easy it is to understand a piece of code: **verbosity** and **complexity**.
Reducing **verbosity** is important, because boilerplate makes a project more difficult to navigate. It also has a tendency to make one's eyes gloss over, and subtle typos/bugs become more likely to slip through.
Reducing **complexity** makes the code more accessible to more people. This is especially important for open-source projects like Flutter, where the code is read by those who make contributions, as well as others who read through source code as they debug their own projects.
<hr>
<br>
The following examples show how pattern-matching might affect these two factors:
<details> <summary><h3>Example 1 (GOOD)</h3> [click to expand]</summary>
```dart
if (ancestor case InheritedElement(:final InheritedTheme widget)) {
themes.add(widget);
}
```
Without using patterns, this might expand to
```dart
if (ancestor is InheritedElement) {
final InheritedWidget widget = ancestor.widget;
if (widget is InheritedTheme) {
themes.add(widget);
}
}
```
Had `ancestor` been a non-local variable, it would need to be "converted" as well:
```dart
final Element ancestor = this.ancestor;
if (ancestor is InheritedElement) {
final InheritedWidget inheritedWidget = ancestor.widget;
if (widget is InheritedTheme) {
themes.add(theme);
}
}
```
</details>
<details> <summary><h3>Example 2 (BAD) </h3> [click to expand]</summary>
```dart
if (widget case PreferredSizeWidget(preferredSize: Size(:final double height))) {
return height;
}
```
Assuming `widget` is a non-local variable, this would expand to:
```dart
final Widget widget = this.widget;
if (widget is PreferredSizeWidget) {
return widget.preferredSize.height;
}
```
<br>
</details>
In both of the examples above, an `if-case` statement simultaneously verifies that an object meets the specified criteria and performs a variable assignment accordingly.
But there are some differences: Example 2 uses a more deeply-nested pattern than Example 1 but makes fewer useful checks.
**Example 1:**
- checks that `ancestor` is an `InheritedElement`
- checks that the inherited element's `widget` is an `InheritedTheme`
**Example 2:**
- checks that `widget` is a `PreferredSizeWidget`
(every `PreferredSizeWidget` has a `size` field, and every `Size` has a `height` field)
<br>
<hr>
I feel hesitant to try presenting a set of cut-and-dry rules as to which scenarios should/shouldn't use pattern-matching, since there are an abundance of different types of patterns, and an abundance of different places where they might be used.
But hopefully the conversations we've had recently will help us converge toward a common intuition of how pattern-matching can best be utilized for improved readability.
<br><br>
- resolves https://github.com/flutter/flutter/issues/152313
- Design Doc: [flutter.dev/go/dart-patterns](https://flutter.dev/go/dart-patterns)
*Replace this paragraph with a description of what this PR is changing or adding, and why. Consider including before/after screenshots.*
*List which issues are fixed by this PR. You must list at least one issue. An issue is not required if the PR fixes something trivial like a typo.*
*If you had to change anything in the [flutter/tests] repo, include a link to the migration guide as per the [breaking change policy].*
Reverts: flutter/flutter#154044
Initiated by: zanderso
Reason for reverting: Version does not exist.
Original PR Author: flutter-pub-roller-bot
Reviewed By: {fluttergithubbot}
This change reverts the following previous change:
This PR was generated by `flutter update-packages --force-upgrade`.
Reverts: flutter/flutter#152487
Initiated by: gmackall
Reason for reverting: I forgot that I need to override the compileSdkVersion in the AGP 8.0 [instance of this test](ef9cd32f5a/dev/devicelab/bin/tasks/android_java17_dependency_smoke_tests.dart (L19))
Original PR Author: gmackall
Reviewed By: {reidbaker}
This change reverts the following previous change:
Updates `compileSdk`, `targetSdk`, and `ndk` versions (former 2 to latest, latter to the version of the ndk we are hosting on CIPD).
Summary of changes:
- Updates mentioned template values
- `compileSdk` 35 requires AGP 8.0+, so updated to 8.1 in many places.
- This also necessitated Gradle upgrades in most places
- This also necessitated moving the `package` xml attribute to the AGP `namespace` field in a couple places (test + template).
- Some tests use the output of `flutter create` but then use intentionally lower AGP versions. [I downgraded the `compileSdk` in these tests.](fee34fd61a)
- [Stopped lockfile generation](82324a2570) script from hitting the `hello_world` example because it uses `.kts` gradle files.
- One test needed [some Gradle options we had already added to templates](6aa187b4b6).
Updates `compileSdk`, `targetSdk`, and `ndk` versions (former 2 to latest, latter to the version of the ndk we are hosting on CIPD).
Summary of changes:
- Updates mentioned template values
- `compileSdk` 35 requires AGP 8.0+, so updated to 8.1 in many places.
- This also necessitated Gradle upgrades in most places
- This also necessitated moving the `package` xml attribute to the AGP `namespace` field in a couple places (test + template).
- Some tests use the output of `flutter create` but then use intentionally lower AGP versions. [I downgraded the `compileSdk` in these tests.](fee34fd61a)
- [Stopped lockfile generation](82324a2570) script from hitting the `hello_world` example because it uses `.kts` gradle files.
- One test needed [some Gradle options we had already added to templates](6aa187b4b6).
Reverts: flutter/flutter#150733
Initiated by: gmackall
Reason for reverting: This breaks apps that use plugins that use `compileSdk` 31, some of which we use in our postsubmit (so it blocks the tree).
Original PR Author: gmackall
Reviewed By: {jason-simmons}
This change reverts the following previous change:
Manual engine roll to https://github.com/flutter/engine/pull/53532, because the roll requires lockfile generation.
Removes these two discontinued plugins from `dev/integration_tests/flutter_gallery`
[`device_info`](https://pub.dev/packages/device_info):
Apparently the video playback doesn't work on iOS simulators (I wasn't able to verify this, as I don't have an iOS simulator installed). I removed the guard against running on those simulators, and replaced with a note in the README.
[`connectivity`](https://pub.dev/packages/connectivity):
This plugin was used to play the bee video from the network. I changed the demo so that the bee video is instead also played from an asset (like its friend the butterfly), and then removed the use of the plugin.
Unblocks the re-land of https://github.com/flutter/engine/pull/53462 (itself a reland ð), because of https://github.com/flutter/flutter/pull/150465#issuecomment-2181403712.
Initial tap is missing sometimes; either its never delivered or it is
delivered before gesture controller is hooked up.
1: Update MemoryTest to have option `requiresTapToStart` guarding the
new paths
2: Update the two perf tests that appear to be flaky to output when
TAPPED is received
3: Update the MemoryTest to keep tapping while waiting for TAPPED
Tested on devicelab:
* setting iterations=1
* removing the timeout before READY
* running tests in a while loop
Before this change, you could get the test to hang often. After this
change you'll see "tapping device... [x]" where x is the counter.
Fixes https://github.com/flutter/flutter/issues/150096
Reverts: flutter/flutter#150287
Initiated by: jtmcdole
Reason for reverting: other memperf tests don't wait for or send a TAPPED; so they fail.
Original PR Author: jtmcdole
Reviewed By: {gaaclarke}
This change reverts the following previous change:
Initial tap is missing sometimes; either its never delivered or it is delivered before gesture controller is hooked up.
1: Update the two perf tests to output when TAPPED is received
2: Update the MemoryTest to keep tapping while waiting for TAPPED
Tested on devicelab:
* setting iterations=1
* removing the timeout before READY
* running tests in a while loop
Before this change, you could get the test to hang often. After this change you'll see "tapping device... [x]" where x is the counter.
Fixes#150096
Initial tap is missing sometimes; either its never delivered or it is delivered before gesture controller is hooked up.
1: Update the two perf tests to output when TAPPED is received
2: Update the MemoryTest to keep tapping while waiting for TAPPED
Tested on devicelab:
* setting iterations=1
* removing the timeout before READY
* running tests in a while loop
Before this change, you could get the test to hang often. After this change you'll see "tapping device... [x]" where x is the counter.
Fixes#150096
