/**
* A ConcreteClass.
*/
class NonNegativeSubtraction extends BinaryOperation
{
private $_a;
private $_b;
public function __construct($a = 0, $b = 0)
{
$this->_a = $a;
$this->_b = $b;
}
protected function _getFirstNumber()
{
return $this->_a;
}
protected function _getSecondNumber()
{
return min($this->_a, $this->_b);
}
protected function _operator($a, $b)
{
return $a - $b;
}
}
$sum = new Sum(84, 56);
//140
echo $sum->getOperationResult(), "\n";
$nonNegativeSubtraction = new NonNegativeSubtraction(9, 14);
//0
echo $nonNegativeSubtraction->getOperationResult();
