yii2-bootstrap/docs/review_2011_11_12_alex.md

Alex's Code Review, 2011.11.12

Overall hierarchy

Generally is OK. Like that Object and Component are now separated. I've generated 2 diagrams under docs/ to see it better as a whole.

The purpose of separating Object from Component is to make Object a super-light base class that supports properties defined by getter/setters. Note that Component is a bit of heavy because it uses two extra member variables to support events and behaviors.

Object

property feature

Is it OK that canGetProperty and canSetProperty will return false for real class members?

Added $checkVar parameter

callbacks and expressions

We're using 5.3. What's the reason to support eval() in evaluateExpression if we have anonymous functions? Is that for storing code as string inside of DB (RBAC)?

If we're going to get rid of eval(), cosider remaning method to something about callback. If not then we definitely need to use anonymous functions in API docs and the guide where possible.

The purpose of evaluateExpression() is to provide a way of evaluating a PHP expression in the context of an object. Will remove it before release if we find no use of it.

mdomba: As eval() is controversial, and anonymous functions can replace all Yii 1 usage of eval() how about removing it from the beginning and add it only if we find it necessary. This way we would not be tempted to stick with eval() and will be forced to first try to find alternatives

Object::create()

__construct issue

Often a class doesn't have __construct implementation and stdClass doesn't have default one either but Object::create() always expects constructor to be defined. See ObjectTest. Either method_exists call or Object::__construct needed.

Added Object::__construct.

How to support object factory like we do with CWidgetFactory?

class ObjectConfig
{
	public function configure($class)
	{
		$config = $this->load($class);
		// apply config to $class
	}

	private function load($class)
	{
		// get class properties from a config file
		// in this method we need to walk all the
		// inheritance hierarchy down to Object itself
		return array(
			'property' => 'value',
			// …
		);
	}
}

Then we need to add __construct to Object (or implement Initalbe):

class Object
{
	public function __construct()
	{
		$conf = new ObjectConfig();
		$conf->configure($this);
	}
}

This way we'll be able to set defaults for any object.

The key issue here is about how to process the config file. Clearly, we cannot do this for every type of component because it would mean an extra file access for every component type

Do we need to support lazy class injection?

Currently there's no way to lazy-inject class into another class property via config. Do we need it? If yes then we can probably extend component config to support the following:

class Foo extends Object
{
	public $prop;
}

class Bar extends Object
{
	public $prop;
}

$config = array(
	'prop' => array(
		'class' => 'Bar',
		'prop' => 'Hello!',
	),
);

$foo = Foo::create($config);
echo $foo->bar->prop;
// will output Hello!

Should it support infinite nesting level?

I don't think we need this. Foo::$prop cannot be an object unless it needs it to be. In that case, it can be defined with a setter in which it can handle the object creation based on a configuration array. This is a bit inconvenient, but I think such usage is not very common.

Why Event is Object?

There's no need to extend from Object. Is there a plan to use Object features later?

To use properties defined via getter/setter.

Behaviors

Overall I wasn't able to use behaviors. See BehaviorTest.

Should behaviors be able to define events for owner components?

Why not? Should be a very good feature in order to make behaviors customizable.

It's a bit hard to implement it efficiently. I tend not to support it for now unless enough people are requesting for it.

Multiple behaviors can be attached to the same component

What if we'll have multiple methods / properties / events with the same name?

The first one takes precedence. This is the same as we do in 1.1.

How to use Behavior::attach?

Looks like it is used by Component::attachBehavior but can't be used without it. Why it's public then? Can we move it to Component?

It's public because it is called by Component. It is in Behavior such that it can be overridden by behavior classes to customize the attach process.

Events

Class itself looks OK. Component part is OK as well but I've not tested it carefully. Overall it seems concept is the same as in Yii1.

Event declaration: the on-method is mostly repetitive for every event. Should we choose a different way of declaring events?

Maybe. People complained previously about too many code for event declaration.

Should we implement some additional event mechanism, such as global events?

Why use two different implementations in a single application?

Exceptions

• Should we convert all errors, warnings and notices to exceptions?

I think not. We used to do this in early versions of 1.0. We found sometimes very mysterious things would happen which makes error fixing harder rather than easier.

Coding style

See docs/code_style.md.