Suggestion: Index signatures that exclude certain names

[amcasey]

Search Terms

index signatures, else, negation

Suggestion

Most immediately inspired by https://github.com/mui-org/material-ui/blob/01b8b09fd6a28d6092ad0b192305ebe8e11c97ea/packages/material-ui-styles/src/withStyles/withStyles.d.ts#L38. The goal is to say that "this type contains all the properties of the base type and for any other property name a CreateCSSProperties will be returned".

I can imagine implementing this as either an "anything else" signature or as an explicit/computed list of excluded names (the added flexibility of which may or may not be desirable).

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.

[amcasey]

I've previously discussed this with @RyanCavanaugh

[jcalz]

Duplicate of #17867

[typescript-bot]

This issue has been marked as a 'Duplicate' and has seen no recent activity. It has been automatically closed for house-keeping purposes.