package joptima;

import java.lang.reflect.*;

/**
 * Mutable parameter.
 * The minimizer calls the set() method on this class during minimization.
 * This has the effect of setting the field on the object that implements
 * the Function interface, so a subsequent Fuction.calculate() call will
 * work with the given values.
 *
 * @author Dejan Vucinic
 */
public class Parameter {

  private Field m_field;
  private Function m_function;
  private String m_name;

  /**
   * Constructor.
   * Remembers which object this parameter belongs to, and constructs
   */
  public Parameter(Function function, String fieldname) throws NoSuchFieldException {
    m_function = function;
    m_field = function.getClass().getField("m_" + fieldname);
    m_name = function.getName() + "." + fieldname;
  }

  public void set(double value) throws IllegalAccessException {
    m_field.setDouble(m_function, value);
  }

  public double get() throws IllegalAccessException {
    return m_field.getDouble(m_function);
  }

}