/**
 * Base class for reactive services.
 * Provides common state management and subscription functionality for all derived services.
 *
 * @typeParam T - The type of data managed by this service
 */
export declare class BaseService<T> {
    /** The current value of the service state */
    protected current: T;
    /** Array of callback functions subscribed to state changes */
    protected _callbacks: ((value: T) => void)[];
    /**
     * Creates a new BaseService instance
     *
     * @param initialValue - The initial state value
     */
    constructor(initialValue: T);
    /**
     * Subscribe to changes in the service value.
     * Callback is immediately invoked with the current value.
     *
     * @param callback - Function to be called when value changes
     * @returns An unsubscribe function that removes this subscription
     */
    subscribe(callback: (value: T) => void): () => void;
    /**
     * Update the service value and notify all subscribers.
     *
     * @param value - New value to set
     */
    set(value: T): void;
    /**
     * Get the current value
     * @returns Current value
     */
    get(): T;
}