Specifications

285
Chapter 14: Versioning
You might encounter some versioning issues when working on Adobe® Flex® applications. When compiling, you
can choose the version of the SDK to use and you can target specific versions of Adobe® Flash® Player. You can
replicate behavior of previous SDK versions. Also, you can design applications that can load modules and other
SWF files that were compiled with different SDKs.
Topics
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .285
Using multiple SDKs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .286
Backward compatibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 286
Targeting Flash Player versions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 295
Overview
When a new version of Flex is released, it usually includes changes to the APIs, compiler, and the user interface
for Adobe® Flex® Builder™. As a result, if you were working on a project but then upgraded your version of the
SDK, you might have to refactor some part of your code to be compatible with the new version. In addition, if the
audience for your application is restricted in what Flash Player it can use, you might have to make certain conces-
sions to ensure that your application runs without errors.
Flex Builder 3 lets you choose different SDKs, based on your needs. This lets you maintain projects in Flex Builder
3 that have not been updated to be compatible with the latest version of the SDK, or lets you use Flex Builder 3
features without having to refactor your Flex 2.0.1 projects. For more information, see “Using multiple SDKs” on
page 286.
The differences between Flex 2.0.1 and Flex 3 go beyond new features. The layout schemes and the styles of many
components have changed. If you want to use Flex 3 features but have your application look and feel the same as
Flex 2.0.1, you can specify the version whose styles you want to use with the
compatibility-version compiler
option. For more information, see “Backward compatibility” on page 286.
With current Flex tools, you can target your application toward a specific version of Flash Player. To do this, you
use the
target-player compiler option. For more information, see “Targeting Flash Player versions” on
page 295.