RE: [aspectj-users] parameter evaluation and advice

["Lendvai Attila" <Attila.Lendvai@xxxxxxxxxxx>]

:: Consider the following advice:
:: 
::     void around(Logger aLog) :
::         call(public * Logger.debug(..))
::         && target(aLog)  {
::             if (aLog.isDebugEnabled()) {
::                 proceed(aLog);
::             } 
::         }
:: 
:: This advice works as expected - it prevents calls to 
:: log.debug(myString) from executing if log is not debugEnabled.  
:: 
:: However, testing for a side effect on myString or examining 
:: byte code reveals that the parameter to the debug() method 
:: ('myString') is being evaluated, even if log is not debugEnabled and
:: proceed() is never called.
:: 
:: I'm not familiar with how AspectJ is implemented, but... is 
:: there a way to prevent parameter evaluation in this example?  

to do this you need a fully dynamic system with proper macro support (a
system/language where code = data is practically true, and has runtime
eval/compile). if you are willing to invest in learning more about the
possibilities you can find a lot of good reading at
http://cliki.tunes.org/index the Learning Lounge section contains a
structured info that you can read/skip base don your knowledge.

i don't say that it couldn't be done by the brilliant aspectj team, but
it would mean partially implementing such a dynamic system (?). i would
be more than happy to see macros/eval/compile in java, but there's
little probability of that.

<dreaming>

oh, well. if only java were not bootstrapped by a VM written in a
different language, but instead a fully self contained system that has
code as first class objects and can generate executables for different
platforms by it's compiler written in itself. but that would be a
different story, a different language...

</dreaming>

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