Difference between #4 and #3 of How to customize Yii core messages?

Yii core messages refer to static text strings in the core Yii framework code
which are meant to be displayed to end-users (e.g. core exception messages,
default validation error messages). Customization of these core messages is
needed in two circumstances:

 * When an application is written for non-English users, these core messages
need to be translated and the framework does not have the required translation.
 * Some core messages need to be modified slightly for various reasons. For
example, the messages are too technical; the messages are inappropriate in
certain scenarios; the messages contain syntax errors. In the last example, bugs
should be reported, but not every application can wait till the bugs are fixed.

In this article, we introduce a technique to customize the core messages in a
systematic way. If you are only interested in customizing a few validation error
messages, you may refer to the article "[How to customize the error message
of a validation rule](/doc/cookbook/1/)".

When Yii displays a core message, it actually undergoes an implicit translation
process with the help of an application component named
"[coreMessages|CApplication::coreMessages]". The component translates
the core message into the [target language|CApplication::language] which is
displayed ultimately. If a translation cannot be found, the original core
message will be displayed, instead. 

The idea here is to customize the `coreMessages` component by changing the place
where it looks for translated messages. We can do so by configuring the
component with the following application configuration:

~~~
[php]
return array(
	......
	'language'=>'de',
	'components'=>array(
		'coreMessages'=>array(
			'basePath'=>'protected/messages',
		),
		......
	),
);
~~~

In the above, we specify that the application is targeted to German users and
the translated messages are located under the directory `protected/messages`.

Next, we need to provide our translations. Under the directory
`protected/messages`, create a subdirectory named `de` which corresponds to the
target language we set in the application configuration. And under the `de`
directory, create a new file named `yii.php`. To this end, we should have the
following directory structure:

~~~
WebRoot/
	protected/
		messages/
			de/
				yii.php
		controllers/
		views/
		......
~~~

Finally, we put message translations in the `yii.php` file. To save time, we may
simply copy the content from `framework/messages/de/yii.php` and modify it as
needed.

> Tip: You may wonder why we would take so much trouble in order to customize
the core messages. Why don't we modify the file `framework/messages/de/yii.php`
directly? The answer is that you should never modify any core framework file. If
you do that, you will face the danger that a future upgrade of the framework may
overwrite your change.

### Links
[Chinese
version](http://dreamneverfall.cn/node/105)version](http://projects.ourplanet.tk/node/105)