# Access Interceptor Scope Localizer Proxy

An access interceptor scope localizer is a smart reference proxy that allows you to dynamically define logic to be executed 
before or after any of the proxied object methods' logic.

It works exactly like the [access interceptor value holder](access-interceptor-value-holder.md), with some minor differences 
in behaviour.

The working concept of an access interceptor scope localizer is to localize scope of a proxied object:

```php
class Example
{
    protected $foo;
    protected $bar;
    protected $baz;

    public function doFoo()
    {
        // ...
    }
}

class ExampleProxy extends Example
{
    public function __construct(Example $example)
    {
        $this->foo = & $example->foo;
        $this->bar = & $example->bar;
        $this->baz = & $example->baz;
    }

    public function doFoo()
    {
        return parent::doFoo();
    }
}
```

This allows creating a mirror copy of the real instance, where any change in the proxy or the real instance is reflected in 
both objects.

The main advantage of this approach is that the proxy is now safe against fluent interfaces, which would break an 
[access interceptor value holder](access-interceptor-value-holder.md) instead.

## Differences with [access interceptor value holder](access-interceptor-value-holder.md):

 * It does **NOT** implement the `ProxyManager\Proxy\ValueHolderInterface`, since the proxy itself does not keep a reference 
   to the original object being proxied
 * In all interceptor methods (see [access interceptor value holder](access-interceptor-value-holder.md)), the `$instance` 
   passed in is the proxy itself. There is no way to gather a reference to the original object right now, and that is mainly 
   to protect from misuse.

## Known limitations

 * It is **NOT** possible to intercept access to public properties
 * It is **NOT** possible to proxy interfaces, since this proxy relies on `parent::method()` calls. Interfaces don't provide 
   a parent method implementation.
 * calling `unset` on a property of an access interceptor scope localizer (or the real instance) will cause the two objects 
   to be un-synchronized, with possible unexpected behaviour.
 * serializing or un-serializing an access interceptor scope localizer (or the real instance) will not cause the real 
   instance (or the proxy) to be serialized or un-serialized
 * methods using `func_get_args()`, `func_get_arg()` and `func_num_arg()` will not function properly for parameters that are 
   not part of the proxied object interface: use 
   [variadic arguments](http://php.net/manual/en/functions.arguments.php#functions.variable-arg-list) instead.

## Example

Here's an example of how you can create and use an access interceptor scope localizer:

```php
<?php

use ProxyManager\Factory\AccessInterceptorScopeLocalizerFactory as Factory;

require_once __DIR__ . '/vendor/autoload.php';

class Foo
{
    public function doFoo()
    {
        echo "Foo!\n";
    }
}

$factory = new Factory();

$proxy = $factory->createProxy(
    new Foo(),
    ['doFoo' => function () { echo "PreFoo!\n"; }],
    ['doFoo' => function () { echo "PostFoo!\n"; }]
);

$proxy->doFoo();
```

This sends something like following to your output:

```
PreFoo!
Foo!
PostFoo!
```

This is similar logic to what you can find in [access interceptor value holder](access-interceptor-value-holder.md).