1. AspectJ Syntax Basics

2. Identify Join Points 1 public class Bit { 2 bool value; 3 void Set() {
value = true;
5 }
6 void Clear() {
value = false;
8 }
9 void Toggle {
10 if(Get()) Set();
11 else clear();
12 }
13 void Get() {
return value;
15 }
16 }

3. Pointcuts Named pointcut AllCall(): call( * *(..)); Anonymous
before(): call( * *(..)) { … }

4. Named Pointcut Syntax [access specifier] pointcut pointcut-
name([args]): pointcut definition

5. Why Named Pointcuts? Pointcut Reuse Separation of two specifications:
Where additional behavior is to be applied?
What is the additional behavior?
Late Binding of Design Decisions

6. Pointcut Reuse & Separation
public pointcut StringArg(String s):
execution( * *(..)) && args(s);
around(String s): StringArg(s) {
/* Omit execution if null argument */ }
/* Omit execution if not valid XML */ }

7. Late Binding abstract aspect Lock { pointcut CriticalSections();
before(): CriticalSections() {
/* Acquire lock */ }
after(): CriticalSections() {
/* Release lock */

8. Late Binding … aspect BufferLock extends Lock {
pointcut CriticalSections():
call(* * Buffer.Write(..)); }

9. Poincut composition pointcut1 && pointcut2 pointcut1 || pointcut2

10. Signatures
Type Signatures
Method Signatures
Field Signatures

11. Example Type Signature
javax..*Model+
Any sub-type of a given type
Any number of characters including period
Any number of characters excluding the period

12. Exercise 1
Write down the type signature to pick out only the sub-types of all the types in the javax package or its direct and indirect subpackages that have a name ending in Model.

13. Example Method Signature
* javax..*.add*Listener(EventListener+)

14. Example Field Signature
!public static * banking..*.*

15. Cflow and Cflowbelow
Cflow (Pointcut) - Captures all join points in the control flow of the join points matched by the specified pointcut, including the join points themselves.
Cflowbelow(Pointcut) – Excludes the matching join points, matches everything below.

16. cflow( execution Account.debit(..))
1 void debit(int amount) {
if( this.getBalance() > amount) {
this.setBalance( this.getBalance() – amount);
4 }
5 int getBalance() {
return db.Query(name, “balance”);
7 }
8 int setBalance(int balance) {
9 db.Update(name, “balance”, balance);
10 }

17. Lexical Pointcuts within( type pattern )
withincode( method or constructor pattern)

18. Identify matches within(Bit)
1 public class Bit {
2 bool value;
3 void Set() {
value = true;
5 }
6 void Clear() {
value = false;
8 }
9 void Toggle {
10 if(Get()) Set();
11 else clear();
12 }
13 void Get() {
return value;
15 }
16 }

19. withincode(* * Bit.*et(..))
1 public class Bit {
2 bool value;
3 void Set() {
value = true;
5 }
6 void Clear() {
value = false;
8 }
9 void Toggle {
10 if(Get()) Set();
11 else clear();
12 }
13 bool Get() {
return value;
15 }
16 }