@@ -193,13 +193,10 @@ please refer to the [Configurations](concept-configurations.md#configuration-for
Using Behaviors <a name="using-behaviors"></a>
---------------
To use a behavior, you first need to attach it to a [[yii\base\Component|component]]. We will describe how to
attach a behavior in the next subsection.
Once a behavior is attached to a component, its usage is straightforward.
To use a behavior, first attach it to a [[yii\base\Component|component]] per the instructions above. Once a behavior is attached to a component, its usage is straightforward.
You can access a *public* member variable or a [property](concept-properties.md) defined by a getter and/or a setter
of the behavior through the component it is attached to, like the following,
of the behavior through the component it is attached to:
```php
// "prop1" is a property defined in the behavior class
...
...
@@ -207,21 +204,21 @@ echo $component->prop1;
$component->prop1=$value;
```
You can also call a *public* method of the behavior similarly,
You can also call a *public* method of the behavior similarly:
```php
// bar() is a public method defined in the behavior class
$component->bar();
// foo() is a public method defined in the behavior class
$component->foo();
```
As you can see, although `$component` does not define `prop1` and `bar()`, they can be used as if they are part
of the component definition.
of the component definition due to the attached behavior.
If two behaviors define the same property or method and they are both attached to the same component,
the behavior that is attached to the component first will take precedence when the property or method is being accessed.
the behavior that is attached to the component *first* will take precedence when the property or method is accessed.
A behavior may be associated with a name when it is attached to a component. If this is the case, you may
access the behavior object using the name, like the following,
Using `TimestampBehavior` <a name="using-timestamp-behavior"></a>
-------------------------
To wrap up, let's take a look at [[yii\behaviors\TimestampBehavior]] - a behavior that supports automatically
updating the timestamp attributes of an [[yii\db\ActiveRecord|Active Record]] when it is being saved.
To wrap up, let's take a look at [[yii\behaviors\TimestampBehavior]]. This behavior supports automatically
updating the timestamp attributes of an [[yii\db\ActiveRecord|Active Record]] model anytime the model is saved (e.g., on insert or update).
First, attach this behavior to the [[yii\db\ActiveRecord|Active Record]] class that you plan to use.
First, attach this behavior to the [[yii\db\ActiveRecord|Active Record]] class that you plan to use:
```php
namespaceapp\models\User;
...
...
@@ -286,13 +280,13 @@ class User extends ActiveRecord
}
```
The behavior configuration above specifies that
The behavior configuration above specifies that when the record is being:
*when the record is being inserted, the behavior should assign the current timestamp to
the `created_at` and `updated_at` attributes;
*when the record is being updated, the behavior should assign the current timestamp to the `updated_at` attribute.
* inserted, the behavior should assign the current timestamp to
the `created_at` and `updated_at` attributes
*updated, the behavior should assign the current timestamp to the `updated_at` attribute
Now if you have a `User` object and try to save it, you will find its `created_at` and `updated_at` are automatically
With that code in place, if you have a `User` object and try to save it, you will find its `created_at` and `updated_at` are automatically
filled with the current timestamp:
```php
...
...
@@ -303,43 +297,41 @@ echo $user->created_at; // shows the current timestamp
```
The [[yii\behaviors\TimestampBehavior|TimestampBehavior]] also offers a useful method
[[yii\behaviors\TimestampBehavior::touch()|touch()]] which will assign the current timestamp
[[yii\behaviors\TimestampBehavior::touch()|touch()]], which will assign the current timestamp
to a specified attribute and save it to the database:
```php
$user->touch('login_time');
```
Comparison with Traits <a name="comparison-with-traits"></a>
Comparing Behaviors with Traits <a name="comparison-with-traits"></a>
----------------------
While behaviors are similar to [traits](http://www.php.net/traits) in that they both "inject" their
properties and methods to the primary class, they differ in many aspects. As explained below, they
both have pros and cons. They are more like complements rather than replacements to each other.
both have pros and cons. They are more like complements to each other rather than alternatives.
### Pros for Behaviors <a name="pros-for-behaviors"></a>
### Reasons to Use Behaviors <a name="pros-for-behaviors"></a>
Behavior classes, like normal classes, support inheritance. Traits, on the other hand,
can be considered as language-supported copy and paste. They do not support inheritance.
Behaviors can be attached and detached to a component dynamically without requiring you to modify the component class.
To use a trait, you must modify the class using it.
Behaviors can be attached and detached to a component dynamically without requiring modification of the component class. To use a trait, you must modify the class using it.
Behaviors are configurable while traits are not.
Behaviors can customize the code execution of a component by responding to its events.
When there is name conflict among different behaviors attached to the same component, the conflict is
automatically resolved by respecting the behavior that is attached to the component first.
Name conflict caused by different traits requires you to manually resolve it by renaming the affected
When there can be name conflicts among different behaviors attached to the same component, the conflicts are
automatically resolved by prioritizing the behavior attached to the component first.
Name conflicts caused by different traits requires manually resolution by renaming the affected
properties or methods.
### Pros for Traits <a name="pros-for-traits"></a>
### Reasons to Use Traits <a name="pros-for-traits"></a>
Traits are much more efficient than behaviors because behaviors are objects which take both time and memory.
Traits are much more efficient than behaviors as behaviors are objects that take both time and memory.
IDEs are more friendly to traits as they are language construct.
