MACROMEDIA FLEX 2-MIGRATING APPLICATIONS TO FLEX 2 Manuel d'utilisateur télécharger pdf (Page 28)

28 ActionScript 2.0 to 3.0

Using external files

This section describes changes to embedding, including, and importing external resources

with ActionScript in your Flex applications.

include

In ActionScript 2.0, the include keyword was preceded by an octothorp: #include. You now

use the keyword without the octothorp, and end the line with a semi-colon. For example:

ActionScript 2.0:

#include "../scripts/thescript.as"

ActionScript 3.0:

include "../scripts/thescript.as";

import

The import keyword lets you reference classes from other packages in your application. For

example, to use a

trace() statement in your custom ActionScript class, you import the

flash.util.trace class. The

import syntax is as follows:

import class;

For example:

import flash.util.trace;

You can optionally import entire packages using the wildcard syntax, as the following example

shows:

import flash.util.*;

However, best practices dictate that you only import the classes you need and not the entire

package. Doing so is better for performance and debugging.

ActionScript 3.0 uses a number of implicit imports to provide direct access to common global

functions such as

trace(). In ActionScript 3.0, the number of implicit imports has been

reduced. For more information, see “Explicit imports” on page 34.

It is important to understand that you should import classes with an import statement rather

than use the full classname in your code. For example, do this:

import mx.formatters.*;

public var f:NumberFormatter = new NumberFormatter();

Rather than this:

public var f:mx.formatters.NumberFormatter = new

mx.formatters.NumberFormatter();

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MACROMEDIA FLEX 2-MIGRATING APPLICATIONS TO FLEX 2 Manuel d'utilisateur Page 28