call vs. execution
When methods and constructors run, there are two interesting times associated with them. That is when they are called, and when they actually execute. AspectJ exposes these times as call and execution join points, respectively, and allows them to be picked out specifically by call and execution pointcuts. So what's the difference between these join points? Well, there are a number of differences: Firstly, the lexical pointcut declarations within and withincode match differently. At a call join point, the enclosing code is that of the call site. This means that call(void m()) && withincode(void m()) will only capture directly recursive calls, for example. At an execution join point, however, the program is already executing the method, so the enclosing code is the method itself: execution(void m()) && withincode(void m()) is the same as execution(void m()). Secondly, the call join point does not capture super calls to non-static methods. This is because such super calls are different in Java, since they don't behave via dynamic dispatch like other calls to non-static methods. The rule of thumb is that if you want to pick a join point that runs when an actual piece of code runs (as is often the case for tracing), use execution, but if you want to pick one that runs when a particular signature is called (as is often the case for production aspects), use call.
When methods and constructors run, there are two interesting times associated with them. That is when they are called, and when they actually execute. AspectJ exposes these times as call and execution join points, respectively, and allows them to be picked out specifically by call and execution pointcuts. So what's the difference between these join points? Well, there are a number of differences: Firstly, the lexical pointcut declarations within and withincode match differently. At a call join point, the enclosing code is that of the call site. This means that call(void m()) && withincode(void m()) will only capture directly recursive calls, for example. At an execution join point, however, the program is already executing the method, so the enclosing code is the method itself: execution(void m()) && withincode(void m()) is the same as execution(void m()). Secondly, the call join point does not capture super calls to non-static methods. This is because such super calls are different in Java, since they don't behave via dynamic dispatch like other calls to non-static methods. The rule of thumb is that if you want to pick a join point that runs when an actual piece of code runs (as is often the case for tracing), use execution, but if you want to pick one that runs when a particular signature is called (as is often the case for production aspects), use call.
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