Declaring properties on functions is not supported

Rule arkts-no-func-props

Severity: error

ArkTS does not support declaring properties on functions because there is no support for objects with dynamically changing layout. Function objects follow this rule and their layout cannot be changed in runtime.

TypeScript

    class MyImage {
        // ...
    }

    function readImage(
        path: string, callback: (err: any, image: MyImage) => void
    )
    {
        // ...
    }

    function readFileSync(path : string) : number[] {
        return []
    }

    function decodeImageSync(contents : number[]) {
        // ...
    }

    readImage.sync = (path: string) => {
        const contents = readFileSync(path)
        return decodeImageSync(contents)
    }

ArkTS

    class MyImage {
        // ...
    }

    async function readImage(
        path: string, callback: (err: Error, image: MyImage) => void
    ) : Promise<MyImage>
    {
        // In real world, the implementation is more complex,
        // involving real network / DB logic, etc.
        return await new MyImage()
    }

    function readImageSync(path: string) : MyImage {
        return new MyImage()
    }

See also

• Recipe 137: globalThis is not supported (arkts-no-globalthis)