Const Debug = True If Debug Then ;Do whatever you want EndIf
Not sure if there are IfDef or IfNotDef directives but this bit of code would amount to the exact same thing.
Also, I've heard, but not tested, that when writing an If statement such as above, the If statement will not be included in the executable if the constant variable Debug is set to false. In other words, your release version won't be cluttered with any of your debugging checks (thereby increasing efficiency).