/**
 * Create a reactive reference to a configuration value.
 *
 * Returns an object with a `value` getter that always fetches the current configuration value.
 * Useful for creating properties that stay synchronized with configuration changes.
 *
 * ### Usage
 *
 * ```typescript
 * import {refValue, Injectable} from "@tsed/di";
 *
 * @Injectable()
 * class Test {
 *   logLevel = refValue<string>("logger.level", "info");
 *   port = refValue<number>("server.port");
 *
 *   constructor() {
 *     console.log(this.logLevel.value); // Always current value
 *   }
 * }
 * ```
 *
 * @typeParam Type The expected type of the value
 * @param expression Dot-notation path to the configuration value
 * @param defaultValue Optional default value if the expression is not found
 * @returns A frozen object with a reactive `value` property
 * @public
 */
export declare function refValue<Type>(expression: string): {
    value: Type | undefined;
};
export declare function refValue<Type>(expression: string, defaultValue: Type | undefined): {
    value: Type;
};