将 PHP 对象设置为全局？
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Set a PHP object global?
提问by wowpatrick
I just started switching my project form the mysql to PDO. In my project a new PDO Object is created more or less right a the beginning of the programm.
我刚开始将我的项目从 mysql 切换到 PDO。在我的项目中，或多或少地在程序开始时创建了一个新的 PDO 对象。
$dbh_pdo = new PDO("mysql:host=$db_url;dbname=$db_database_name", $db_user, $db_password);
Now I would like to use this handler (is that the correct name?) in some functions and classes. Is there a way to make objects global just like variables or am I trying something unspeakably stupid, because I couldn't find anything when searching the web ...
现在我想在一些函数和类中使用这个处理程序（这是正确的名称吗？）。有没有办法让对象像变量一样全局化，或者我是否在尝试一些难以形容的愚蠢行为，因为我在搜索网络时找不到任何东西......
回答by netcoder
Yes, you can make objects global just like any other variable:
是的，您可以像任何其他变量一样使对象成为全局对象：
$pdo = new PDO('something');
function foo() {
global $pdo;
$pdo->prepare('...');
}
You may also want to check out the Singleton pattern, which basically is a global, OO-style.
您可能还想查看 Singleton 模式，它基本上是一种全局的 OO 风格。
That being said, I'd recommend you not to use globals. They can be a pain when debugging and testing, because it's hard to tell who modified/used/accessed it because everything can. Their usage is generally considered a bad practice. Consider reviewing your design a little bit.
话虽如此，我建议您不要使用 globals。在调试和测试时，它们可能会很痛苦，因为很难分辨谁修改/使用/访问了它，因为一切都可以。它们的使用通常被认为是一种不好的做法。考虑稍微一下您的设计。
I don't know how your application looks like, but say you were doing this:
我不知道你的应用程序是什么样子，但说你是这样做的：
class TableCreator {
public function createFromId($id) {
global $pdo;
$stmt = $pdo->prepare('SELECT * FROM mytable WHERE id = ?');
$stmt->execute(array($id));
$rows = $stmt->fetchAll(PDO::FETCH_ASSOC);
foreach ($rows as $row) {
// do stuff
}
}
}
You should dothat instead:
你应该这样做：
class TableCreator {
protected $pdo;
public function __construct(PDO $pdo) {
$this->pdo = $pdo;
}
public function createFromId($id) {
$stmt = $this->pdo->prepare('SELECT * FROM mytable WHERE id = ?');
$stmt->execute(array($id));
$rows = $stmt->fetchAll(PDO::FETCH_ASSOC);
foreach ($rows as $row) {
// do stuff
}
}
}
Since the TableCreatorclass here requires a PDO object to work properly, it makes perfect sense to pass one to it when creating an instance.
由于TableCreator这里的类需要一个 PDO 对象才能正常工作，因此在创建实例时将一个传递给它是非常有意义的。
回答by Jeff Hubbard
You'll use $GLOBALS['dbh_pdo']instead of $dbh_pdoinside any functions. Or you can use the global keyword, and use $dbh_pdo(i.e. global $dbh_pdo).
您将在任何函数中使用$GLOBALS['dbh_pdo']而不是使用$dbh_pdo。或者您可以使用 global 关键字，并使用$dbh_pdo(ie global $dbh_pdo)。
回答by Jeremy
You could also try using a Singleton to pass back a PDO object to you. That way you only ever have one PDO object (and one database connection) in any request which saves on memory/server resources.
您也可以尝试使用 Singleton 将 PDO 对象传回给您。这样一来，您在任何请求中都只有一个 PDO 对象（和一个数据库连接），从而节省了内存/服务器资源。
