| // Copyright (c) 2015, the Dart project authors. Please see the AUTHORS file |
| // for details. All rights reserved. Use of this source code is governed by a |
| // BSD-style license that can be found in the LICENSE file. |
| |
| import 'package:analyzer/dart/ast/ast.dart'; |
| import 'package:analyzer/dart/ast/visitor.dart'; |
| |
| import '../analyzer.dart'; |
| |
| const _desc = |
| r'Place the `super` call last in a constructor initialization list.'; |
| |
| const _details = r''' |
| |
| From the [style guide](https://dart.dev/guides/language/effective-dart/style/): |
| |
| **DO** place the `super` call last in a constructor initialization list. |
| |
| Field initializers are evaluated in the order that they appear in the |
| constructor initialization list. If you place a `super()` call in the middle of |
| an initializer list, the superclass's initializers will be evaluated right then |
| before evaluating the rest of the subclass's initializers. |
| |
| What it doesn't mean is that the superclass's constructor body will be executed |
| then. That always happens after all initializers are run regardless of where |
| `super` appears. It's vanishingly rare that the order of initializers matters, |
| so the placement of `super` in the list almost never matters either. |
| |
| Getting in the habit of placing it last improves consistency, visually |
| reinforces when the superclass's constructor body is run, and may help |
| performance. |
| |
| **GOOD:** |
| ``` |
| View(Style style, List children) |
| : _children = children, |
| super(style) { |
| ``` |
| |
| **BAD:** |
| ``` |
| View(Style style, List children) |
| : super(style), |
| _children = children { |
| ``` |
| |
| **DEPRECATED:** In Dart 2, it is a compile-time error if a superinitializer |
| appears in an initializer list at any other position than at the end so this |
| rule is made redundant by the Dart analyzer's basic checks and is no longer |
| necessary. |
| |
| The rule will be removed in a future Linter release. |
| '''; |
| |
| class SuperGoesLast extends LintRule implements NodeLintRule { |
| SuperGoesLast() |
| : super( |
| name: 'super_goes_last', |
| description: _desc, |
| details: _details, |
| maturity: Maturity.deprecated, |
| group: Group.style); |
| |
| @override |
| void registerNodeProcessors( |
| NodeLintRegistry registry, LinterContext context) { |
| final visitor = _Visitor(this); |
| registry.addConstructorDeclaration(this, visitor); |
| } |
| } |
| |
| class _Visitor extends SimpleAstVisitor<void> { |
| final LintRule rule; |
| |
| _Visitor(this.rule); |
| |
| @override |
| void visitConstructorDeclaration(ConstructorDeclaration node) { |
| var last = node.initializers.length - 1; |
| |
| for (var i = 0; i <= last; ++i) { |
| var init = node.initializers[i]; |
| if (init is SuperConstructorInvocation && i != last) { |
| rule.reportLint(init); |
| } |
| } |
| } |
| } |