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/**
 *  Copyright (c) 2010-2012, The StaccatoCommons 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.defs;

/**
 * {@link Evaluable}s are boolean conditions over an argument that can be tested
 * using its {@link #eval(Object)} message.
 * 
 * {@link Evaluable} has the same semantics that an {@link Applicable} of
 * {@link Boolean} return type, but is provided for ease of coding. Concrete
 * implementors should implement {@link Applicable} as well.
 * 
 * 
 * @author flbulgarelli
 * 
 * @param 
 *          the type of object that can be evaluated
 * 
 * @see Applicative Recomendations for implementing
 */
@Applicative
public interface Evaluable {

  /**
   * Evaluates an argument. If the argument evaluates to true is said to satisfy
   * or meet this condition.
   * 
   * {@link Evaluable} implementors should not try to handle nulls. Instead, the
   * preferred way of getting a null safe {@link Evaluable} is composing it with
   * the null or non-null predicates from staccato-commons-lang:
   * 
   *    * Predicates.null_().or(theActualEvaluable)
   * Predicates.notNull().and(theActualEvaluable)
   * 
   * 
   * @param argument
   *          the argument to evaluate.
   * 
   * @return if the argument meets this evaluable condition
   */
  boolean eval(T argument);

}