AspectJ Syntax Basics

Com S 362: Object-Oriented Analysis and Design

AspectJ Syntax Basics

2 Com S 362: Object-Oriented Analysis and Design

2


Identify Join Points

1 public class Bit {

2 bool value;

3 void Set() {

4 value = true;

5 }

6 void Clear() {

7 value = false;

8 }

9 void Toggle {

10 if(Get()) Set();

11 else clear();

12 }

13 void Get() {

14 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 & Separationpublic pointcut StringArg(String s):

execution( * *(..)) && args(s);

around(String s): StringArg(s) { /* Omit execution if null argument */

}around(String s): StringArg(s) { /* Omit execution if not valid XML */

}


7


Late Bindingabstract 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

! pointcut


10


Signatures Type Signatures

Method Signatures

Field Signatures


11


Example Type Signature

javax..*Model+

Any number of characters including period

Any number of characters excluding the period

Any sub-type of a given type


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) {

2 if( this.getBalance() > amount) {

3 this.setBalance( this.getBalance() – amount);

4 }

5 int getBalance() {

6 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)


2 bool value;

3 void Set() {

4 value = true;

5 }

6 void Clear() {

7 value = false;

8 }

9 void Toggle {

10 if(Get()) Set();

11 else clear();

12 }

13 void Get() {

14 return value;

15 }

16 }


19


withincode(* * Bit.*et(..))


2 bool value;

3 void Set() {

4 value = true;

5 }

6 void Clear() {

7 value = false;

8 }

9 void Toggle {

10 if(Get()) Set();

11 else clear();

12 }

13 bool Get() {

14 return value;

15 }

16 }

AspectJ Syntax Basics

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