Extend createMethodSignature and updateMethodSignature with 'modifiers' argument

[wessberg]

Search Terms

updateMethodSignature, createMethodSignature

Suggestion

It should be possible to provide an array of Modifiers (or undefined) to the createMethodSignature and updateMethodSignature functions.

Use Cases

When using the TypeScript compiler APIs, TypeScript provides numerous create and update functions that can be used to generate an AST, for example from Custom Transformers. However, for MethodSignatures, which may have modifiers such as the static keyword, there's no option to create or update their modifiers. This breaks one of my libraries which sole purpose is to simply deep-clone a TypeScript node. A workaround is to manually patch the modifiers, however I hope this can be part of the function (as it is for others, like createPropertySignature and updatePropertySignature).

Examples

import {createMethodSignature, createNodeArray, createModifier, SyntaxKind} from "typescript";

createMethodSignature(
    createNodeArray([
        createModifier(SyntaxKind.StaticKeyword)
    ]),
    node.typeParameters,
    node.parameters,
    node.type,
    node.name,
    node.questionToken
);

However, the above example would be a breaking change since the first parameter expects a NodeArray of type parameters, so an alternative solution would be to accept it as the last argument.

Checklist

My suggestion meets these guidelines:

• This wouldn't be a breaking change in existing TypeScript/JavaScript code
• This wouldn't change the runtime behavior of existing JavaScript code
• This could be implemented without emitting different JS based on the types of the expressions
• This isn't a runtime feature (e.g. library functionality, non-ECMAScript syntax with JavaScript output, etc.)
• This feature would agree with the rest of TypeScript's Design Goals.

[wessberg]

As part of #35282, I can see that you have added modifiers as the first argument to the new createMethodSignature and updateMethodSignature methods in the NodeFactory interface. Since this is part of the TypeScript v4.0.0, feel free to close this issue.