Question::handle_question PHP Method

    public function handle_question()
    {
        $this->_strategy->do_method();
    }

{
    // 具体策略角色C
    public function do_method()
    {
        echo 'do method 3';
    }
}
class Question
{
    // 环境角色
    private $_strategy;
    public function __construct(Strategy $strategy)
    {
        $this->_strategy = $strategy;
    }
    public function handle_question()
    {
        $this->_strategy->do_method();
    }
}
// client
$strategyA = new ConcreteStrategyA();
$question = new Question($strategyA);
$question->handle_question();
$strategyB = new ConcreteStrategyB();
$question = new Question($strategyB);
$question->handle_question();
$strategyC = new ConcreteStrategyC();
$question = new Question($strategyC);
$question->handle_question();