介绍

require_once "PEAR.php";

class FileContainer extends PEAR
{
    var $file = '';
    var $contents = '';
    var $modified = 0;

    function FileContainer($file)
    {
        $this->PEAR(); // this calls the parent class constructor

		                   //这些调用了父类的构造器
        $fp = fopen($file, "r");
        if (!is_resource($fp)) {
            return;
        }
	$this->file = $file;
        while ($data = fread($fp, 2048)) {
            $this->contents .= $data;
    	}
        fclose($fp);
    }

    function append($str)
    {
        $this->contents .= $str;
        $this->modified++;
    }

	//这个析构函数的命名很像构造函数.
	// 而且有个下划线
    function _FileContainer()
    {
        if ($this->modified) {
            $fp = fopen($this->file, "w");
            if (!is_resource($fp)) {
                return;
            }
            fwrite($fp, $this->contents);
            fclose($fp);
        }
    }
}

$fileobj =& new FileContainer("testfile");
$fileobj->append("this ends up at the end of the file\n");

//当请求完成php关闭,$fileobj的析构函数就被调用和刷新了磁盘上的文件.

function mysockopen($host = "localhost", $port = 8090)
{
    $fp = fsockopen($host, $port, $errno, $errstr);
    if (!is_resource($fp)) {
        return new PEAR_Error($errstr, $errno);
    }
    return $fp;
}

$sock = mysockopen();
if (PEAR::isError($sock)) {
    print "mysockopen error: ".$sock->getMessage()."\n";
}

class TCP_Socket extends PEAR
{
    var $sock;

    function TCP_Socket()
    {
        $this->PEAR();
    }

    function connect($host, $port)
    {
        $sock = fsockopen($host, $port, $errno, $errstr);
        if (!is_resource($sock)) {
            return $this->raiseError($errstr, $errno);
        }
    }
}

$sock = new TCP_Socket;
$sock->setErrorHandling(PEAR_ERROR_DIE);
$sock->connect('localhost', 8090);
print "still alive\n";