Thursday, April 19, 2007

The ways to express pointcuts, the choice is yours

From the non-AOP programmers' perspective, the pointcut mini-language in AspectJ seems to be a bit difficult to learn. Before they can start writing some aspects, they need to know background concepts about join points, the way how to quantify them with a combination of pointcut designators, and the way how to express advice codes.

I cannot argue this because making pointcut languages simple yet powerful is quite an active research in the AOP area.

Some workaround to solve this problem could be having different kind of way to express pointcuts in one framework. So this means we're going to have several mini-languages inside the host language for describing aspects. They are what I'm going to implement for my AOP subsystem for Groovy.

For example, call() PCD is a quite common one you often use, so having:

Test.around['test*'] = {} instead of around(): call(Test.test*(..)) { }

can reduce the learning curve.

But when, the power of the basic pointcut language is not enough, you can use the full version of pointcut language, like this:

static aspect = {
def p = pointcut{
pcall('public *':'set*') & pcall( ... ) &
around(p) { context ->

The choice of expressing pointcuts is just yours.

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