如何根据 php 中的数组值动态创建对象？

Question

我想动态创建与我的 $instance 数组中存在的对象一样多的对象（例如 domain1_com 和 domain2_com）并为它们指定数组值的名称（例如 domain1_com 和 domain2_com) 所以我可以通过这些名称访问它（例如 domain1_com->example()）。

可能吗？我尝试过类似的方法，但显然不起作用。

    class myClass
    {
        public static function getInstances()
        {
            // I connect to the database and execute the query
            $sql = "SELECT * FROM my_table";    
            $core = Core::getInstance();
            $stmt = $core->dbh->prepare($sql);

            if ($stmt->execute()) {
                $results = $stmt->fetchAll(PDO::FETCH_ASSOC);
            }

            // Read values in my array
            foreach ($results as $instance) {

                $obj = $instance["domain"]);
                // return 2 values: domain1_com and domain2_com

                $obj = new myClass();
            }
        }

        public function example()
        {
            echo "This is an instance";
        }
    }

    myClass::getInstances();

    $domain1_com->example();
    $domain2_com->example();

Answer 1

可以使用可变变量。

$name = "foo";
$$name = new bar();

与

相同

$foo = new bar();

您无法在该方法之外访问在 getInstances 中创建的变量。它们是本地的，而不是全球的。

试试这个代码：

class myClass
{
    public static function getInstances()
    {
        $results = array('domain1_com', 'domain2_com');

        foreach ($results as $instance) {
            $$instance = new myClass();
            // This is equivalent to "$domainX_com = new myClass();".
            // Writing that code here would define a _local_ variable named 'domainX_com'.
            // This being a method inside a class any variables you define in here are _local_,
            // so you can't access them' _outside_ of this method ('getInstances')
        }

        // this will work, we are inside 'getInstances'
        $domain1_com->example();
        $domain2_com->example();
    }

    public function example()
    {
        echo "This is an instance";
    }
}

myClass::getInstances();

// this won't work. $domainX_com are not accessible here. they only exist _inside_ 'getInstances'
// It's basic OOP.
// so this code will crash
$domain1_com->example();
$domain2_com->example();

它将产生这个输出：

This is an instance

This is an instance

E_NOTICE : type 8 -- Undefined variable: domain1_com -- at line 32

E_ERROR : type 1 -- Call to a member function example() on a non-object -- at line 32

您需要一种方法来访问这些变量。我会用这个：

class myClass
{
    private static $instances = array();
    public static function getInstances()
    {
        $results = array('domain1_com', 'domain2_com');

        foreach ($results as $instanceName) {
            self::$instances[$instanceName] = new myClass();
        }
    }

    public static function getInstance($instanceName) {
        return self::$instances[$instanceName];
    }

    public function example()
    {
        echo "This is an instance";
    }
}

myClass::getInstances();

// this will work
myClass::getInstance('domain1_com')->example();
myClass::getInstance('domain2_com')->example();

如何根据 php 中的数组值动态创建对象？

How can I create dynamically objects based on array values in php?

php

static

instance