How to implement this feature in PHP?

When accessing member that doesn't exist, autom开发者_Go百科atically creates the object.

$obj = new ClassName();
$newObject = $ojb->nothisobject;

Is it possible?

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Use the magic overloading functions

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You can achieve this kind of functionality with Interceptor __get()

class ClassName
{
function __get($propertyname){
$this->{$propertyname} = new $propertyname();
return $this->{$propertyname}
}
}

Though example in the previous post will work just fine also when the attribute is changed to public so you can access it from outside.

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If you mean lazy initalization, this is one of many ways:

class SomeClass
{
    private $instance;

    public function getInstance() 
    {
        if ($this->instance === null) {
            $this->instance = new AnotherClass();
        }
        return $this->instance;
    }
}

---

$obj = new MyClass();

$something = $obj->something; //instance of Something

Use the following Lazy loading pattern:

<?php

class MyClass
{
    /**
     * 
     * @var something
     */
    protected $_something;

    /**
     * Get a field
     *
     * @param  string $name
     * @throws Exception When field does not exist
     * @return mixed
     */
    public function __get($name)
    {
        $method = '_get' . ucfirst($name);

        if (method_exists($this, $method)) {
            return $this->{$method}();
        }else{
            throw new Exception('Field with name ' . $name . ' does not exist');
        }
    }

    /**
     * Lazy loads a Something
     * 
     * @return Something
     */
    public function _getSomething()
    {
        if (null === $this->_something){
            $this->_something = new Something();
        }

        return $this->_something;
    }
}