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feat(eslint-plugin): [consistent-generic-constructors] add rule (#4924)
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82
packages/eslint-plugin/docs/rules/consistent-generic-constructors.md
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| # `consistent-generic-constructors` | ||
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| Enforces specifying generic type arguments on type annotation or constructor name of a constructor call. | ||
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| When constructing a generic class, you can specify the type arguments on either the left-hand side (as a type annotation) or the right-hand side (as part of the constructor call): | ||
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| ```ts | ||
| // Left-hand side | ||
| const map: Map<string, number> = new Map(); | ||
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| // Right-hand side | ||
| const map = new Map<string, number>(); | ||
| ``` | ||
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| This rule ensures that type arguments appear consistently on one side of the declaration. | ||
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| ## Options | ||
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| ```jsonc | ||
| { | ||
| "rules": { | ||
| "@typescript-eslint/consistent-generic-constructors": [ | ||
| "error", | ||
| "constructor" | ||
| ] | ||
| } | ||
| } | ||
| ``` | ||
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| This rule takes a string option: | ||
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| - If it's set to `constructor` (default), type arguments that **only** appear on the type annotation are disallowed. | ||
| - If it's set to `type-annotation`, type arguments that **only** appear on the constructor are disallowed. | ||
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| ## Rule Details | ||
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| The rule never reports when there are type parameters on both sides, or neither sides of the declaration. It also doesn't report if the names of the type annotation and the constructor don't match. | ||
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| ### `constructor` | ||
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| <!--tabs--> | ||
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| #### ❌ Incorrect | ||
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| ```ts | ||
| const map: Map<string, number> = new Map(); | ||
| const set: Set<string> = new Set(); | ||
| ``` | ||
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| #### ✅ Correct | ||
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| ```ts | ||
| const map = new Map<string, number>(); | ||
| const map: Map<string, number> = new MyMap(); | ||
| const set = new Set<string>(); | ||
| const set = new Set(); | ||
| const set: Set<string> = new Set<string>(); | ||
| ``` | ||
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| ### `type-annotation` | ||
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| <!--tabs--> | ||
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| #### ❌ Incorrect | ||
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| ```ts | ||
| const map = new Map<string, number>(); | ||
| const set = new Set<string>(); | ||
| ``` | ||
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| #### ✅ Correct | ||
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| ```ts | ||
| const map: Map<string, number> = new Map(); | ||
| const set: Set<string> = new Set(); | ||
| const set = new Set(); | ||
| const set: Set<string> = new Set<string>(); | ||
| ``` | ||
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| ## When Not To Use It | ||
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| You can turn this rule off if you don't want to enforce one kind of generic constructor style over the other. |
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104 changes: 104 additions & 0 deletions
104
packages/eslint-plugin/src/rules/consistent-generic-constructors.ts
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| import { AST_NODE_TYPES } from '@typescript-eslint/utils'; | ||
| import { createRule } from '../util'; | ||
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| type MessageIds = 'preferTypeAnnotation' | 'preferConstructor'; | ||
| type Options = ['type-annotation' | 'constructor']; | ||
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| export default createRule<Options, MessageIds>({ | ||
| name: 'consistent-generic-constructors', | ||
| meta: { | ||
| type: 'suggestion', | ||
| docs: { | ||
| description: | ||
| 'Enforce specifying generic type arguments on type annotation or constructor name of a constructor call', | ||
| recommended: 'strict', | ||
| }, | ||
| messages: { | ||
| preferTypeAnnotation: | ||
| 'The generic type arguments should be specified as part of the type annotation.', | ||
| preferConstructor: | ||
| 'The generic type arguments should be specified as part of the constructor type arguments.', | ||
| }, | ||
| fixable: 'code', | ||
| schema: [ | ||
| { | ||
| enum: ['type-annotation', 'constructor'], | ||
| }, | ||
| ], | ||
| }, | ||
| defaultOptions: ['constructor'], | ||
| create(context, [mode]) { | ||
| const sourceCode = context.getSourceCode(); | ||
| return { | ||
| VariableDeclarator(node): void { | ||
| const lhs = node.id.typeAnnotation?.typeAnnotation; | ||
| const rhs = node.init; | ||
| if ( | ||
| !rhs || | ||
| rhs.type !== AST_NODE_TYPES.NewExpression || | ||
| rhs.callee.type !== AST_NODE_TYPES.Identifier | ||
| ) { | ||
| return; | ||
| } | ||
| if ( | ||
| lhs && | ||
| (lhs.type !== AST_NODE_TYPES.TSTypeReference || | ||
| lhs.typeName.type !== AST_NODE_TYPES.Identifier || | ||
| lhs.typeName.name !== rhs.callee.name) | ||
| ) { | ||
| return; | ||
| } | ||
| if (mode === 'type-annotation') { | ||
| if (!lhs && rhs.typeParameters) { | ||
| const { typeParameters, callee } = rhs; | ||
| const typeAnnotation = | ||
| sourceCode.getText(callee) + sourceCode.getText(typeParameters); | ||
| context.report({ | ||
| node, | ||
| messageId: 'preferTypeAnnotation', | ||
| fix(fixer) { | ||
| return [ | ||
| fixer.remove(typeParameters), | ||
| fixer.insertTextAfter(node.id, ': ' + typeAnnotation), | ||
| ]; | ||
| }, | ||
| }); | ||
| } | ||
| return; | ||
| } | ||
| if (mode === 'constructor') { | ||
| if (lhs?.typeParameters && !rhs.typeParameters) { | ||
| const hasParens = | ||
| sourceCode.getTokenAfter(rhs.callee)?.value === '('; | ||
| const extraComments = new Set( | ||
| sourceCode.getCommentsInside(lhs.parent!), | ||
| ); | ||
| sourceCode | ||
| .getCommentsInside(lhs.typeParameters) | ||
| .forEach(c => extraComments.delete(c)); | ||
| context.report({ | ||
| node, | ||
| messageId: 'preferConstructor', | ||
| *fix(fixer) { | ||
| yield fixer.remove(lhs.parent!); | ||
| for (const comment of extraComments) { | ||
| yield fixer.insertTextAfter( | ||
| rhs.callee, | ||
| sourceCode.getText(comment), | ||
| ); | ||
| } | ||
| yield fixer.insertTextAfter( | ||
| rhs.callee, | ||
| sourceCode.getText(lhs.typeParameters), | ||
| ); | ||
| if (!hasParens) { | ||
| yield fixer.insertTextAfter(rhs.callee, '()'); | ||
| } | ||
| }, | ||
| }); | ||
| } | ||
| } | ||
| }, | ||
| }; | ||
| }, | ||
| }); |
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