AS3 Conditional Compilation

From FlashDevelop

ActionScript 3 supports conditional compilation and FlashDevelop offers a nice integration of this feature.

Read: Using Conditional Compilation

FlashDevelop default constants

FlashDevelop automatically sets 6 constants:

• CONFIG::debug - true if "Debug" configuration is active
• CONFIG::release - true if "Release" configuration is active
• CONFIG::timeStamp - "24/12/2010" (ie. DD/MM/YYYY) as the date of build.
• CONFIG::air - true if the target platform is AIR or AIR Mobile
• CONFIG::mobile - true it the target platform is AIR Mobile
• CONFIG::desktop - true it the target platform is AIR

You may wonder why the timestamp does not contain the time: that's because setting a different value on each compile was causing serious memory leaks when using the Flex Compiler SHell. Maybe that's fixed in Flex 4 SDK, maybe not.

User-defined constants

In the Project Properties, Compiler Options tab, you can populate the "Compiler Constants" list.

Each line should contain a pair: NAMESPACE::variable_name,value with:

• NAMESPACE - any identifier,
• variable_name - any identifier,
• value - an AS3-valid constant value (true, false, 0, 1.5, "Company Name") or expression (1 > 2, 4 - 1).

Usage example

A Compiler Const can be used as an externally defined constant value or expression:

public const COMPANY:String = CONFIG::companyName;

private function someFunction() {
  if (CONFIG::debug == true) {
    trace("This code only executed in Debug configuration (but still compiled).");
  }
  trace("Built: " + CONFIG::timeStamp);
}

Or it can also be used to generate different code paths:

private function someFunction() {
  CONFIG::debug {
    trace("This code is NOT compiled in Release configuration");
    return;
  }
  trace("This code never executed in Debug configuration - and apparently not even compiled");
}

CONFIG::debug
private function someFunction() {
  trace("debug version");
}

CONFIG::release
private function someFunction() {
  trace("release version");
}