org.elder.sourcerer.MutableAggregate Maven / Gradle / Ivy

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package org.elder.sourcerer;

import org.jetbrains.annotations.NotNull;

/**
 * An mutable specialization of Aggregate, implicitly bound to an aggregate projection, that
 * adds supports for updating state by applying events.
 *
 * @param  The type representing state of an aggregate (as relevant to the domain where it
 *                 is used).
 * @param  The type of events that can be applied to the aggregate (in the current domain).
 */
public interface MutableAggregate extends Aggregate {
    /**
     * Applies a single event to the aggregate state, updating both the encapsulated state, and the
     * local log of events applied to it.
     *
     * @param event The event to apply.
     */
    void apply(@NotNull TEvent event);

    /**
     * Applies a list of events to the aggregate state, updating both the encapsulated state,
     * and the local log of events applied to it.
     *
     * @param events The events to apply.
     */
    void apply(@NotNull Iterable events);

    /**
     * Resets the aggregate instance so that it contains the same state as the current one, but with
     * a new version - effectively representing the aggregate in a state after it has been persisted
     * and read back. The new source state will be the current state of the aggregate and the
     * version set to the specified value, and the list of pending events will be reset.
     *
     * @param version The new version of the aggregate.
     */
    void rebase(int version);
}