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Consolidated CHANGELOG entry for 2.3.0.

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I added an intro to the UI as code stuff and then merged all of the
changes from the previous dev releases.

Change-Id: I0726268adcf5838a24dfee1cacd13e730b004090
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/99736
Commit-Queue: Bob Nystrom <rnystrom@google.com>
Reviewed-by: Vijay Menon <vsm@google.com>
Reviewed-by: Alexander Thomas <athom@google.com>
This commit is contained in:
Bob Nystrom 2019-04-18 21:27:51 +00:00
parent cf4444b803
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CHANGELOG.md
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@ -1,36 +1,207 @@
## 2.2.1-dev.XX.0
(Add new changes here, and they will be copied to the change section for the
next dev version)
## 2.3.0
The focus in this release is on the new "UI-as-code" language features which
make collections more expressive and declarative.
### Language
Flutter is growing rapidly, which means many Dart users are building UI in code
out of big deeply-nested expressions. Our goal with 2.3.0 was to [make that kind
of code easier to write and maintain][ui-as-code]. Collection literals are a
large component, so we focused on three features to make collections more
powerful. We'll use list literals in the examples below, but these features also
work in map and set literals.
[ui-as-code]: https://medium.com/dartlang/making-dart-a-better-language-for-ui-f1ccaf9f546c
#### Spread
Placing `...` before an expression inside a collection literal unpacks the
result of the expression and inserts its elements directly inside the new
collection. Where before you had to write something like this:
```dart
CupertinoPageScaffold(
child: ListView(children: [
Tab2Header()
]..addAll(buildTab2Conversation())
..add(buildFooter())),
);
```
Now you can write this:
```dart
CupertinoPageScaffold(
child: ListView(children: [
Tab2Header(),
...buildTab2Conversation(),
buildFooter()
]),
);
```
If you the expression might evaluate to null and you want to treat that as
equivalent to zero elements, you can use the null-aware spread `?...`.
#### Collection if
Sometimes you might want to include one or more elements in a collection only
under certain conditions. If you're lucky, you can use a `?:` operator to
selectively swap out a single element, but if you want to exchange more than one
or omit elements, you are forced to write imperative code like this:
```dart
Widget build(BuildContext context) {
var children = [
IconButton(icon: Icon(Icons.menu)),
Expanded(child: title)
];
if (isAndroid) {
children.add(IconButton(icon: Icon(Icons.search)));
}
return Row(children: children);
}
```
We now allow `if` inside collection literals to conditionally omit or (with
`else`) swap out an element:
```dart
Widget build(BuildContext context) {
return Row(
children: [
IconButton(icon: Icon(Icons.menu)),
Expanded(child: title),
if (isAndroid)
IconButton(icon: Icon(Icons.search)),
],
);
}
```
Unlike the existing `?:` operator, a collection `if` can be composed with
spreads to conditionally include or omit multiple items:
```dart
Widget build(BuildContext context) {
return Row(
children: [
IconButton(icon: Icon(Icons.menu)),
if (isAndroid) ...[
Expanded(child: title),
IconButton(icon: Icon(Icons.search)),
]
],
);
}
```
#### Collection for
In many cases, the higher-order methods on Iterable give you a declarative way
to modify a collection in the context of a single expression. But some
operations, especially involving both transforming and filtering, can be
cumbersome to express in a functional style.
To solve this problem, you can use `for` inside a collection literal. Each
iteration of the loop produces an element which is then inserted in the
resulting collection. Consider the following code:
```dart
var command = [
engineDartPath,
frontendServer,
...fileSystemRoots.map((root) => "--filesystem-root=$root"),
...entryPoints
.where((entryPoint) => fileExists("lib/$entryPoint.json"))
.map((entryPoint) => "lib/$entryPoint"),
mainPath
];
```
With a collection `for`, the code becomes simpler:
```dart
var command = [
engineDartPath,
frontendServer,
for (var root in fileSystemRoots) "--filesystem-root=$root",
for (var entryPoint in entryPoints)
if (fileExists("lib/$entryPoint.json")) "lib/$entryPoint",
mainPath
];
```
As you can see, all three of these features can be freely composed. For full
details of the changes, see [the official proposal][ui-as-code proposal].
[ui-as-code proposal]: https://github.com/dart-lang/language/blob/master/accepted/future-releases/unified-collections/feature-specification.md
**Note: These features are not currently supported in *const* collection
literals. In a future release, we intend to relax this restriction and allow
spread and collection `if` inside const collections.**
### Core library changes
#### `dart:isolate`
* Added `debugName` property to `Isolate`.
* Added `debugName` optional parameter to `Isolate.spawn` and
`Isolate.spawnUri`.
#### `dart:core`
* RegExp patterns can now use lookbehind assertions.
* RegExp patterns can now use named capture groups and named backreferences.
Currently, named group matches can only be retrieved in Dart either by the
implicit index of the named group or by downcasting the returned Match
object to the type RegExpMatch. The RegExpMatch interface contains methods
for retrieving the available group names and retrieving a match by group
name.
### Dart VM
* The VM service now requires an authentication code by default. This behavior
can be disabled by providing the `--disable-service-auth-codes` flag.
* The VM service now requires an authentication code by default. This behavior
can be disabled by providing the `--disable-service-auth-codes` flag.
### Tool Changes
* Support for deprecated flags '-c' and '--checked' has been removed.
#### Linter
### Dart for the Web
The Linter was updated to `0.1.86` which includes the following changes:
#### dart2js
* new lint: `prefer_inlined_adds`
* new lint: `prefer_for_elements_to_map_fromIterable`
* new lint: `prefer_if_elements_to_conditional_expressions`
* new lint: `diagnostic_describe_all_properties`
A binary format was added to dump-info. The old JSON format is still available
and provided by default, but we are starting to deprecate it. The new binary
format is more compact and cheaper to generate. On some large apps we tested, it
was 4x faster to serialize and used 6x less memory.
#### Other Tools
To use the binary format today, use `--dump-info=binary`, instead of
`--dump-info`.
## 2.2.1-dev.3.1
What to expect next?
* Cherry-pick 245576a096a2da54ef21d664d37d1f50f6f8dbb7 to dev
* Cherry-pick a47b4ad2b8683cc8a82aa0ff89da2db7a3be27a3 to dev
* Cherry-pick 9a2b222cba94126591b5d985a42d40c704a73c90 to dev
* The [visualizer tool][visualizer] will not be updated to support the new
binary format, but you can find several command-line tools at
`package:dart2js_info` that provide similar features to those in the
visualizer.
### Tool Changes
* The command-line tools in `package:dart2js_info` also work with the old JSON
format, so you can start using them even before you enable the new format.
* In a future release `--dump-info` will default to `--dump-info=binary`. At
that point, there will be an option to fallback to the JSON format, but the
visualizer tool will be deprecated.
* A release after that, the JSON format will no longer be available from
dart2js, but may be available from a command-line tool in
`package:dart2js_info`.
[visualizer]: https://dart-lang.github.io/dump-info-visualizer/
### Tools
#### dartfmt
@ -39,103 +210,25 @@ The Linter was updated to `0.1.86` which includes the following changes:
* Properly format trailing commas in assertions.
* Improve indentation of adjacent strings in argument lists.
## 2.2.1-dev.3.0
### Dart VM
* Support for deprecated flags '-c' and '--checked' has been removed
### Core library changes
#### `dart:isolate`
* Added `debugName` property to `Isolate`.
* Added `debugName` optional parameter to `Isolate.spawn` and
`Isolate.spawnUri`.
### Tool Changes
#### dartfmt
* Tweak set literal formatting to follow other collection literals.
* Add support for "UI as code" features.
#### Linter
The Linter was updated to `0.1.83` which includes the following changes:
The Linter was updated to `0.1.86`, which includes the following changes:
* updated `file_names` to skip prefixed-extension Dart files (e.g., `.css.dart`, `.g.dart`)
* miscellaneous rule documentation fixes
* fixed NPE in `avoid_shadowing_type_parameters`
* added linter version numbering for use in analyzer summaries
* fixed type utilities to handle inheritance cycles
* fixed `unnecessary_parenthesis` false positives
## 2.2.1-dev.2.0
## 2.2.1-dev.1.1
* Cherry-pick 567d552de8ff93d704111467e7f3bf3b896ab684 to dev
* Cherry-pick 4ca57befd707a0309e384472a566c084eef0e56e to dev
## 2.2.1-dev.1.0
* Support for deprecated flags '-c' and '--checked' has been removed
* RegExp patterns can now use lookbehind assertions.
* RegExp patterns can now use named capture groups and named backreferences.
Currently, named group matches can only be retrieved in Dart either by
the implicit index of the named group or by downcasting the returned Match
object to the type RegExpMatch. The RegExpMatch interface contains methods
for retrieving the available group names and retrieving a match by group name.
### Tool Changes
* Added the following lints: `prefer_inlined_adds`,
`prefer_for_elements_to_map_fromIterable`,
`prefer_if_elements_to_conditional_expressions`,
`diagnostic_describe_all_properties`.
* Updated `file_names` to skip prefixed-extension Dart files (`.css.dart`,
`.g.dart`, etc.).
* Fixed false positives in `unnecessary_parenthesis`.
#### Pub client
* Added a CHANGELOG validator that complains if you `pub publish` without mentioning the current
version.
* Removed validation of library names when doing `pub publish`.
* Added support for `pub global activate`ing package from a custom pub URL.
* Added subcommand: `pub logout`. Logs you out of the current session.
* Fix: Use default server for `pub uploader` command.
#### dart2js
* `--dump-info=binary`
A binary format was added to dump-info. The old JSON format is still
available and provided by default, but we are starting to deprecate it.
The new binary format is more compact and cheaper to generate. On some large
apps we tested, it was 4x faster to serialize and used 6x less memory.
To use it today, use `--dump-info=binary`, instead of `--dump-info`.
What to expect next?
* The [visualizer tool][visualizer] will not be updated to support this new
format, but you can find several command-line tools at
`package:dart2js_info` that provide similar features to those in the
visualizer.
* The command-line tools in `package:dart2js_info` also work with the old
JSON format, so you can start using it even before you enable the new
format.
* In a future release `--dump-info` will default to `--dump-info=binary`. At
that point, there will be an option to fallback to the JSON format, but the
visualizer tool will be deprecated.
* A release after that, the JSON format will no longer be available from
dart2js, but may be availabe from a command-line tool in
`package:dart2js_info`.
[visualizer]: https://dart-lang.github.io/dump-info-visualizer/
## 2.2.1-dev.0.0
* Cherry-pick 6f8415245d4dd298730facf83e03de69fc29bbd3 to dev
* Cherry-pick e7d263b05f7f66d15f778df60ee60625e9a3c5f4 to dev
* Cherry-pick dc8a56bc0ece296915c7016e0a8241c7068eca18 to dev
* Added a CHANGELOG validator that complains if you `pub publish` without
mentioning the current version.
* Removed validation of library names when doing `pub publish`.
* Added support for `pub global activate`ing package from a custom pub URL.
* Added subcommand: `pub logout`. Logs you out of the current session.
## 2.2.0 - 2019-02-26