org.scijava.Contextual Maven / Gradle / Ivy

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package org.scijava;

import org.scijava.plugin.Parameter;
import org.scijava.service.Service;

/**
 * An object that belongs to a SciJava application context.
 * 
 * @author Lee Kamentsky
 * @author Curtis Rueden
 */
public interface Contextual {

	/**
	 * Gets the application context to which the object belongs.
	 * 
	 * @see #getContext()
	 * @throws NullContextException if the context has not yet been set via
	 *           {@link #setContext(Context)}.
	 */
	Context context();

	/**
	 * Gets the application context to which the object belongs, or null if
	 * {@link #setContext(Context)} has not yet been called on this object.
	 * 
	 * @see #context()
	 */
	Context getContext();

	/**
	 * Sets the application context to which the object belongs.
	 * 
	 * Typically this method simply delegates to {@link Context#inject(Object)},
	 * and should be called only once to populate the context. Most contextual
	 * objects do not support later alteration of the context, and will throw
	 * {@link IllegalStateException} if this method is invoked again.
	 * 
	 * 
	 * @see Context#inject(Object)
	 * @throws IllegalStateException If the object already has a context.
	 * @throws IllegalArgumentException If the object has a required
	 *           {@link Service} parameter (see {@link Parameter#required()})
	 *           which is not available from the context.
	 */
	default void setContext(final Context context) {
		context.inject(this);
	}


}