Darin Boyd Dot Com

 
We begin by using <strong>require_once</strong> to reference the <strong>Rule.php</strong> file containing our base class.  In my setup, the <strong>Rule.php</strong> file is in the same directory as  our new class.  We inherit from <strong>Rule</strong> using the <strong>extends</strong> key word.  We declare the <strong>Min</strong> and <strong>Max</strong> member variables.  These variables are declared as protected so that you could create other classes based on our new class which would have access to the Min and Max member variables.
<pre lang="php">// Public State Methods
 
	/**
	 * Minimum length allowed for string.
	 *
	 * @return number
	 */
	public function GetMin()
	{
		return $this-&gt;m_Min;
	}
 
	/**
	 * Sets minimum allowed length for string.
	 *
	 * @param number $value
	 */
	public function SetMin($value)
	{
		$this-&gt;m_Min = $value;
	}
 
	/**
	 * Maximum length allowed for string.
	 *
	 * @return number
	 */
	public function GetMax()
	{
		return $this-&gt;m_Max;
	}
 
	/**
	 * Sets maximum allowed length for string.
	 *
	 * @param number $value
	 */
	public function SetMax($value)
	{
		$this-&gt;m_Max = $value;
	}

	// Constructors
 
	/**
	 * Constructor
	 * @param string $_ruleName
	 * @param string $_propertyName
	 * @param string $_min
	 * @param string $_max
	 *
	 */
	public function __construct($_ruleName, $_propertyName, $_min, $_max)
	{
		parent::__construct($_ruleName, $_propertyName, '');
 
		$this->m_Min = $_min;
		$this->m_Max = $_max;
 
		// check the max and min values
		$this->CheckValues();
 
		// set the display text
		$this->CalculateDisplayText();
 
	}

// Overrides
 
	public function Validate($_objectToValidate)
	{
		// Check the values again to make sure the rule is set up properly.
 
		$_MethodName = 'Get' . $this->m_PropertyName;
		$this->m_PropertyValue = $_objectToValidate->$_MethodName();
 
		$this->CheckValues();
 
		$_MinOnly = $this->m_Min > 0 && $this->m_Max == 0;
		$_MaxOnly = $this->m_Max > 0 && $this->m_Min == 0;
		$_MaxAndMin = $this->m_Min > 0 && $this->m_Max > 0 && $this->m_Min < $this->m_Max;
		$_Len = strlen($this->m_PropertyValue);
 
		if($_MinOnly == true)
		{
			$this->m_IsValid = $_Len >= $this->m_Min;
			return;
		}
 
		if($_MaxOnly == true)
		{
			$this->m_IsValid = $_Len <= $this->m_Max;
			return;
		}
 
		if($_MaxAndMin == true)
		{
			$this->m_IsValid = ($_Len >= $this->m_Min)
			&& ($_Len <= $this->m_Max);
 
			return;
		}
 
	}

	// Helper Methods
 
	/**
	 * Figures out how to display the rule text to the user based on the
	 * values of Min and Max.
	 *
	 */
	private function CalculateDisplayText()
	{
		if($this->m_Min == 0 && $this->m_Max > 0)	// we have a rule where only the max has been set
		{
			$this->m_DisplayText = $this->m_PropertyName . ' may be no longer than ' . $this->m_Max . ' characters in length.';
		}
 
		if($this->m_Min > 0 && $this->m_Max == 0)	// we have a rule where only the min has been set
		{
			$this->m_DisplayText = $this->m_PropertyName . ' must be at least ' . $this->m_Min . ' characters in length.';
		}
 
		if($this->m_Min > 0 && $this->m_Max > 0 && $this->m_Min < $this->m_Max)	// we have a rule where min and max have been set
		{
			$this->m_DisplayText = $this->m_PropertyName . ' must be between ' . $this->m_Min . ' and ' . $this->m_Max . ' characters in length.';
		}
	}
 
	/**
	 * Checks values for min and max set by the programmer.
	 * Min must be less than max if max is greater than zero.
	 * Max must be greater than min if min is greater than zero.
	 * Neither may be a negative number.
	 * Both values may not be equal to zero at the same time.
	 *
	 */
	private function CheckValues()
	{
		// check for negative values
		if($this->m_Min < 0 || $this->m_Max < 0)
		{
			throw new Exception('Min or Max values may not be less than zero.');
		}
 
		// check for double zeros.
		if($this->m_Min == 0 && $this->m_Max == 0)
		{
			throw new Exception('Min or Max values may not both be set to zero.');
		}
 
		// check for min less than max when max is set
		if($this->m_Max > 0 && $this->m_Min >= $this->m_Max)
		{
			throw new Exception('If Max is set to a non zero number, Min must be less than Max.');
		}
 
		// check for max greater than min when min is set
		if($this->m_Min > 0 && $this->m_Max <= $this->m_Min && $this->m_Max != 0)
		{
			throw new Exception('If Min is set to a non zero number, Max must be greater than Min.');
		}
 
	}
 
}
?>