Editing Aspect-oriented programming (section)

===AspectJ's join-point model===
{{Main article|AspectJ}}
{{unordered list
| The join points in AspectJ include method or constructor call or execution, the initialization of a class or object, field read and write access, and exception handlers. They do not include loops, super calls, throws clauses, or multiple statements.
| Pointcuts are specified by combinations of ''primitive pointcut designators'' (PCDs).

"Kinded" PCDs match a particular kind of join point (e.g., method execution) and often take a Java-like signature as input. One such pointcut looks like this:
<syntaxhighlight lang="aspectj">
execution(* set*(*))
</syntaxhighlight>
This pointcut matches a method-execution join point, if the method name starts with "<code>set</code>" and there is exactly one argument of any type.

"Dynamic" PCDs check runtime types and bind variables. For example,
<syntaxhighlight lang="aspectj">
this(Point)
</syntaxhighlight>
This pointcut matches when the currently executing object is an instance of class <code>Point</code>. Note that the unqualified name of a class can be used via Java's normal type lookup.

"Scope" PCDs limit the lexical scope of the join point. For example:
<syntaxhighlight lang="aspectj">
within(com.company.*)
</syntaxhighlight>
This pointcut matches any join point in any type in the <code>com.company</code> package. The ''<code>*</code>'' is one form of the wildcards that can be used to match many things with one signature.

Pointcuts can be composed and named for reuse. For example:
<syntaxhighlight lang="aspectj">
pointcut set() : execution(* set*(*) ) && this(Point) && within(com.company.*);
</syntaxhighlight>
This pointcut matches a method-execution join point, if the method name starts with "<code>set</code>" and <code>this</code> is an instance of type <code>Point</code> in the <code>com.company</code> package. It can be referred to using the name "<code>set()</code>".

| Advice specifies to run at (before, after, or around) a join point (specified with a pointcut) certain code (specified like code in a method). The AOP runtime invokes Advice automatically when the pointcut matches the join point. For example:
<syntaxhighlight lang="aspectj">
after() : set() {
  Display.update();
}
</syntaxhighlight>

This effectively specifies: "if the ''<code>set()</code>'' pointcut matches the join point, run the code <code>Display.update()</code> after the join point completes."}}