| import 'package:http/http.dart' as http; | |
| import 'dart:convert'; | |
| main() async { | |
| const pubUrl = "https://pub.dartlang.org/api/packages/protobuf"; | |
| var response = await http.get(Uri.parse(Uri.encodeFull(pubUrl))); | |
| if (response.statusCode == 200) { | |
| PkgInfo info = PkgInfo(json.decode(response.body)); | |
| print('Package ${info.name}, v ${info.latest.pubspec.version}'); | |
| } else { |
| // Some code in this file depends on the 'link-time sets and maps' feature, | |
| // cf. https://github.com/dart-lang/language/issues/371. The basic idea is that | |
| // a link-time set/map can be declared in one library L, and any library L1 that | |
| // imports L can contain contributions to said set/map (you can do `add` on a | |
| // `Set` and `[]=` on a `Map`), and those operations occur before run time. | |
| // For each of the contributions (`add` or `[]=` on a link time collection), the | |
| // operation can be made conditional on the existence of some other entity (or, | |
| // in general, on a boolean expression whose basic predicates is those entities). | |
| // For instance, we could have `myLinkTimeSet.add(5) if C;`, which means that `5` | |
| // will be added to `myLinkTimeSet` if and only if the class `C` is still contained |
| enum Key { | |
| key1, | |
| key2; | |
| T mapFor<T>({ | |
| required T Function() key1, | |
| required T Function() key2, | |
| }) { | |
| switch (this) { | |
| case Key.key1: return key1(); |
| // ---------------------------------------------------------------------- | |
| // Basic example, hypothetical code only. | |
| // typeclass Index<inout X, in Y> { | |
| // X X.operator [](Y y); | |
| // } | |
| // instance Index<int, int> { | |
| // int int.operator [](int y) => this + y; | |
| // } |
| // define an example struct, make it printable | |
| #[derive(Debug)] | |
| struct Foo; | |
| // an example trait | |
| trait Bar { | |
| fn baz(&self); | |
| } | |
| // implement the trait for Foo |
| /* | |
| Several examples, separated by '-----' lines. | |
| We probably want to use a regular type variable declaration list plus | |
| a constraint specification list (to request a dispatcher object for a | |
| specific typeclass instance), so I'm using `where` clauses in various | |
| headers. | |
| Dispatcher objects are holders of functions, and there is no particular | |
| notion of a receiver, so we're likely to benefit _greatly_ from sound |
| void main() { | |
| AnimatedContainer( | |
| SizedBox( | |
| height: 57, | |
| Row([ | |
| if (widget.icon != null) | |
| SizedBox(height: 29, width: 29, widget.icon), | |
| Expanded( | |
| Column([ | |
| const SizedBox(height: 8.5), |
| abstract class Person { | |
| String name; | |
| String address; | |
| } | |
| class DelegatorPerson implements Person { | |
| DelegateePerson delegatee; | |
| DelegatorPerson(this.delegatee); | |
| String get name => delegatee.name(this); | |
| set name(String value) => delegatee.nameSet(this, value); |
| main() { | |
| new Dog().feed("some food"); | |
| } | |
| abstract class Pet { | |
| void feed(String food); | |
| void pet(); | |
| } | |
| class Dog = Pet with FeedableDog, PettableDog; |
This document may be obsolete, please double-check against the review containing the current version and, if it exists, the version in the SDK repository.
Author: eernst@.
Version: 0.4 (2018-08-14).