'Kevin Moore' via Dart Announcements
2017-04-21 15:52:31 UTC
Check out the announcement
<http://news.dartlang.org/2017/04/dart-123-better-strong-mode-support.html>
and the changelog
<https://github.com/dart-lang/sdk/blob/master/CHANGELOG.md>!
1.23.0
<https://github.com/dart-lang/sdk/blob/master/CHANGELOG.md#strong-mode-1>Strong
Mode
- Breaking change - it is now a strong mode error if a mixin causes a
name conflict between two private members (field/getter/setter/method) from
a different library. (SDK issue 28809
<https://github.com/dart-lang/sdk/issues/28809>).
lib1.dart:
class A {
int _x;
}
class B {
int _x;
}
lib2.dart:
import 'lib1.dart';
class C extends A with B {}
error ⢠The private name _x, defined by B, conflicts with the same name defined by A at tmp/lib2.dart:3:24 ⢠private_collision_in_mixin_application
-
Breaking change - strong mode will prefer the expected type to infer
generic types, functions, and methods (SDK issue 27586
<https://github.com/dart-lang/sdk/issues/27586>).
main() {
List<Object> foo = /*infers: <Object>*/['hello', 'world'];
var bar = /*infers: <String>*/['hello', 'world'];
}
-
Strong mode inference error messages are improved (SDK issue 29108
<https://github.com/dart-lang/sdk/issues/29108>).
import 'dart:math';
test(Iterable/* fix is to add <num> here */ values) {
num n = values.fold(values.first as num, max);
}
Now produces the error on the generic function "max":
Couldn't infer type parameter 'T'.
Tried to infer 'dynamic' for 'T' which doesn't work:
Function type declared as '<T extends num>(T, T) â T'
used where '(num, dynamic) â num' is required.
Consider passing explicit type argument(s) to the generic.
-
Strong mode supports overriding fields, @virtual is no longer required
(SDK issue 28120 <https://github.com/dart-lang/sdk/issues/28120>).
class C {
int x = 42;
}class D extends C {
get x {
print("x got called");
return super.x;
}
}
main() {
print(new D().x);
}
-
Strong mode down cast composite warnings are no longer issued by
default. (SDK issue 28588 <https://github.com/dart-lang/sdk/issues/28588>
).
void test() {
List untyped = [];
List<int> typed = untyped; // No down cast composite warning
}
To opt back into the warnings, add the following to the .analysis_options
<https://www.dartlang.org/guides/language/analysis-options> file for your
project.
analyzer:
errors:
strong_mode_down_cast_composite: warning
<https://github.com/dart-lang/sdk/blob/master/CHANGELOG.md#core-library-changes-1>Core
library changes
- dart:core
- Added Uri.isScheme function to check the scheme of a URI. Example:
uri.isScheme("http"). Ignores case when comparing.
- Make UriData.parse validate its input better. If the data is
base-64 encoded, the data is normalized wrt. alphabet and padding, and it
contains invalid base-64 data, parsing fails. Also normalizes non-base-64
data.
- dart:io
- Added functions File.lastAccessed, File.lastAccessedSync,
File.setLastModified, File.setLastModifiedSync, File.setLastAccessed,
and File.setLastAccessedSync.
- Added {Stdin,Stdout}.supportsAnsiEscapes.
<https://github.com/dart-lang/sdk/blob/master/CHANGELOG.md#dart-vm-1>Dart VM
- Calls to print() and Stdout.write*() now correctly print unicode
characters to the console on Windows. Calls to Stdout.add*() behave as
before.
<https://github.com/dart-lang/sdk/blob/master/CHANGELOG.md#tool-changes-1>Tool
changes
-
Analysis
- dartanalyzer now follows the same rules as the analysis server to find
an analysis options file, stopping when an analysis options file is found:
- Search up the directory hierarchy looking for an analysis
options file.
- If analyzing a project referencing the Flutter
<https://flutter.io/> package, then use the default Flutter
analysis options
<https://github.com/flutter/flutter/blob/master/packages/flutter/lib/analysis_options_user.yaml> found
in package:flutter.
- If in a Bazel workspace, then use the analysis options in
package:dart.analysis_options/default.yamlif it exists.
- Use the default analysis options rules.
- In addition, specific to dartanalyzer:
- an analysis options file can be specified on the command line
via --options and that file will be used instead of searching for
an analysis options file.
- any analysis option specified on the command line (e.g. --strong
or --no-strong) takes precedence over any corresponding value
specified in the analysis options file.
-
Dartium, dart2js, and DDC
- Imports to dart:io are allowed, but the imported library is not
supported and will likely fail on most APIs at runtime. This change was
made as a stopgap measure to make it easier to write libraries that share
code between platforms (like package http). This might change again
when configuration specific imports are supported.
-
Pub
- Now sends telemetry data to pub.dartlang.org to allow better
understanding of why a particular package is being accessed.
- pub publish
- Warns if a package imports a package that's not a dependency
from within lib/ or bin/, or a package that's not a dev dependency
from within benchmark/, example/, test/ or tool/.
- No longer produces "UID too large" errors on OS X. All packages
are now uploaded with the user and group names set to "pub".
- No longer fails with a stack overflow when uploading a package
that uses Git submodules.
- pub get and pub upgrade
- Produce more informative error messages if they're run directly
in a package that uses Flutter.
- Properly unlock SDK and path dependencies if they have a new
version that's also valid according to the user's pubspec.
-
dartfmt
- Support new generic function typedef syntax.
- Make the precedence of cascades more visible.
- Fix a couple of places where spurious newlines were inserted.
- Correctly report unchanged formatting when reading from stdin.
- Ensure space between - and --. Code that does this is pathological,
but it technically meant dartfmt could change the semantics of the code.
- Preserve a blank line between enum cases.
- Other small formatting tweaks.
--
For more news and information, visit https://plus.google.com/+dartlang
To join the conversation, visit https://groups.google.com/a/dartlang.org/
<http://news.dartlang.org/2017/04/dart-123-better-strong-mode-support.html>
and the changelog
<https://github.com/dart-lang/sdk/blob/master/CHANGELOG.md>!
1.23.0
<https://github.com/dart-lang/sdk/blob/master/CHANGELOG.md#strong-mode-1>Strong
Mode
- Breaking change - it is now a strong mode error if a mixin causes a
name conflict between two private members (field/getter/setter/method) from
a different library. (SDK issue 28809
<https://github.com/dart-lang/sdk/issues/28809>).
lib1.dart:
class A {
int _x;
}
class B {
int _x;
}
lib2.dart:
import 'lib1.dart';
class C extends A with B {}
error ⢠The private name _x, defined by B, conflicts with the same name defined by A at tmp/lib2.dart:3:24 ⢠private_collision_in_mixin_application
-
Breaking change - strong mode will prefer the expected type to infer
generic types, functions, and methods (SDK issue 27586
<https://github.com/dart-lang/sdk/issues/27586>).
main() {
List<Object> foo = /*infers: <Object>*/['hello', 'world'];
var bar = /*infers: <String>*/['hello', 'world'];
}
-
Strong mode inference error messages are improved (SDK issue 29108
<https://github.com/dart-lang/sdk/issues/29108>).
import 'dart:math';
test(Iterable/* fix is to add <num> here */ values) {
num n = values.fold(values.first as num, max);
}
Now produces the error on the generic function "max":
Couldn't infer type parameter 'T'.
Tried to infer 'dynamic' for 'T' which doesn't work:
Function type declared as '<T extends num>(T, T) â T'
used where '(num, dynamic) â num' is required.
Consider passing explicit type argument(s) to the generic.
-
Strong mode supports overriding fields, @virtual is no longer required
(SDK issue 28120 <https://github.com/dart-lang/sdk/issues/28120>).
class C {
int x = 42;
}class D extends C {
get x {
print("x got called");
return super.x;
}
}
main() {
print(new D().x);
}
-
Strong mode down cast composite warnings are no longer issued by
default. (SDK issue 28588 <https://github.com/dart-lang/sdk/issues/28588>
).
void test() {
List untyped = [];
List<int> typed = untyped; // No down cast composite warning
}
To opt back into the warnings, add the following to the .analysis_options
<https://www.dartlang.org/guides/language/analysis-options> file for your
project.
analyzer:
errors:
strong_mode_down_cast_composite: warning
<https://github.com/dart-lang/sdk/blob/master/CHANGELOG.md#core-library-changes-1>Core
library changes
- dart:core
- Added Uri.isScheme function to check the scheme of a URI. Example:
uri.isScheme("http"). Ignores case when comparing.
- Make UriData.parse validate its input better. If the data is
base-64 encoded, the data is normalized wrt. alphabet and padding, and it
contains invalid base-64 data, parsing fails. Also normalizes non-base-64
data.
- dart:io
- Added functions File.lastAccessed, File.lastAccessedSync,
File.setLastModified, File.setLastModifiedSync, File.setLastAccessed,
and File.setLastAccessedSync.
- Added {Stdin,Stdout}.supportsAnsiEscapes.
<https://github.com/dart-lang/sdk/blob/master/CHANGELOG.md#dart-vm-1>Dart VM
- Calls to print() and Stdout.write*() now correctly print unicode
characters to the console on Windows. Calls to Stdout.add*() behave as
before.
<https://github.com/dart-lang/sdk/blob/master/CHANGELOG.md#tool-changes-1>Tool
changes
-
Analysis
- dartanalyzer now follows the same rules as the analysis server to find
an analysis options file, stopping when an analysis options file is found:
- Search up the directory hierarchy looking for an analysis
options file.
- If analyzing a project referencing the Flutter
<https://flutter.io/> package, then use the default Flutter
analysis options
<https://github.com/flutter/flutter/blob/master/packages/flutter/lib/analysis_options_user.yaml> found
in package:flutter.
- If in a Bazel workspace, then use the analysis options in
package:dart.analysis_options/default.yamlif it exists.
- Use the default analysis options rules.
- In addition, specific to dartanalyzer:
- an analysis options file can be specified on the command line
via --options and that file will be used instead of searching for
an analysis options file.
- any analysis option specified on the command line (e.g. --strong
or --no-strong) takes precedence over any corresponding value
specified in the analysis options file.
-
Dartium, dart2js, and DDC
- Imports to dart:io are allowed, but the imported library is not
supported and will likely fail on most APIs at runtime. This change was
made as a stopgap measure to make it easier to write libraries that share
code between platforms (like package http). This might change again
when configuration specific imports are supported.
-
Pub
- Now sends telemetry data to pub.dartlang.org to allow better
understanding of why a particular package is being accessed.
- pub publish
- Warns if a package imports a package that's not a dependency
from within lib/ or bin/, or a package that's not a dev dependency
from within benchmark/, example/, test/ or tool/.
- No longer produces "UID too large" errors on OS X. All packages
are now uploaded with the user and group names set to "pub".
- No longer fails with a stack overflow when uploading a package
that uses Git submodules.
- pub get and pub upgrade
- Produce more informative error messages if they're run directly
in a package that uses Flutter.
- Properly unlock SDK and path dependencies if they have a new
version that's also valid according to the user's pubspec.
-
dartfmt
- Support new generic function typedef syntax.
- Make the precedence of cascades more visible.
- Fix a couple of places where spurious newlines were inserted.
- Correctly report unchanged formatting when reading from stdin.
- Ensure space between - and --. Code that does this is pathological,
but it technically meant dartfmt could change the semantics of the code.
- Preserve a blank line between enum cases.
- Other small formatting tweaks.
--
For more news and information, visit https://plus.google.com/+dartlang
To join the conversation, visit https://groups.google.com/a/dartlang.org/
--
For other discussions, see https://groups.google.com/a/dartlang.org/
For HOWTO questions, visit http://stackoverflow.com/tags/dart
To file a bug report or feature request, go to http://www.dartbug.com/new
---
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For other discussions, see https://groups.google.com/a/dartlang.org/
For HOWTO questions, visit http://stackoverflow.com/tags/dart
To file a bug report or feature request, go to http://www.dartbug.com/new
---
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