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Library of annotations that express restrictions, that can be used to indicate preconditions, postconditions and invariants over objects and messages, focused on documentation reuse.

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/**
 *  Copyright (c) 2011, The Staccato-Commons Team
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU Lesser General Public License as published by
 *  the Free Software Foundation; version 3 of the License.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU Lesser General Public License for more details.
 */

package net.sf.staccatocommons.restrictions.effect;

import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Inherited;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

import net.sf.staccatocommons.restrictions.Restriction;
import net.sf.staccatocommons.restrictions.value.Immutable;

/**
 * Transparent is a {@link Restriction} that applies to methods that are
 * referentially transparent - their invocations can be replaced by its return
 * value. In other words, are {@link SideEffectFree} and return always equal
 * results for equals arguments.
 * 
 * When applied to types, it means that all its methods are {@link Transparent}.
 * As a consequence, statefull classes that are annotated this way
 * must be immutable, as otherwise, changes of state would
 * eventually impact on changes in results. Thus there is no reason no annotate
 * {@link Transparent} classes as {@link Immutable}, as it is implicit.
 * 
 * Being {@link SideEffectFree} necessary for being {@link Transparent}, there
 * is no reason no annotate {@link Transparent} classes or methods as
 * {@link SideEffectFree}, as it is implicit.
 * 
 * As a consequence of being {@link Immutable}, {@link Transparent} classes are
 * thread safe.
 * 
 * @author flbulgarelli
 * @see Referential
 *      transparency
 * @see SideEffectFree
 * @see Immutable
 */
@Documented
@Inherited
@Restriction
@Retention(RetentionPolicy.SOURCE)
@Target({ ElementType.TYPE, ElementType.METHOD })
public @interface Transparent {

}