import 'reflect-metadata';
import type { ReloadEvents } from './reload';
import type { Vars } from './vars.class';
/**
 * It is unconventional to use raw values from process.env or somewhere
 * else because it will not be autodocumented. Instead developer is strongly
 * encouraged to extends this abstract class and annotate all fields with
 * @Property() decorator providing nesessary metadata.
 */
export declare class Config {
    private readonly events;
    /**
     * Keys are prefixed and sources are added.
     */
    private readonly propertiesMetadata;
    constructor(events: ReloadEvents);
    static isConfigSection(value: Function): value is typeof Config;
    onUpdate(fn: (keys: string[]) => void): void;
    read(vars: Vars): string[];
    tryUpdate(vars: Vars): void;
}