Function assertNotDecorated

packages/mobx/src/api/decorators.ts:53–65

(prototype: object, annotation: Annotation, key: PropertyKey)

}

function assertNotDecorated(prototype: object, annotation: Annotation, key: PropertyKey) {
    if (__DEV__ && !isOverride(annotation) && hasProp(prototype[storedAnnotationsSymbol], key)) {
        const fieldName = `${prototype.constructor.name}.prototype.${key.toString()}`
        const currentAnnotationType = prototype[storedAnnotationsSymbol][key].annotationType_
        const requestedAnnotationType = annotation.annotationType_
        die(
            `Cannot apply '@${requestedAnnotationType}' to '${fieldName}':` +
                `\nThe field is already decorated with '@${currentAnnotationType}'.` +
                `\nRe-decorating fields is not allowed.` +
                `\nUse '@override' decorator for methods overridden by subclass.`
        )
    }
}

/**
 * Collects annotations from prototypes and stores them on target (instance)