RE: [aspectj-users] Declare error

["Ron Bodkin" <rbodkin@xxxxxxxxxxxxxx>]

Jitesh,

Your code does a good job of testing for calls to non-default constructors. However, I believe Andre wants to check whether a class does NOT have a default constructor. AspectJ's statically resolvable pointcuts don't allow you to test for such conditions. You could test for this case with a run time check right after loading the class:

aspect EnforceRequiresDefaultConstructor {
    after() returning : staticinitialization(RequiresDefaultConstructor+) {
        Class clazz = thisJoinPointStaticPart.getSourceLocation().getWithinType();
        try {
             clazz.getConstructor(new Class[0]);
        } catch (NoSuchMethodException e) {
             throw new IllegalStateException("class "+clazz+"without default constructor");
        } catch (SecurityException e) {
             //logWarning?
        }
   }
}

public class RequiresDefaultConstructor {
    public static void main(String args[]) throws Exception {
        Legal l = new Legal("hi");
        Class.forName("Illegal"); // should bomb
    }  
}

class Legal extends RequiresDefaultConstructor {
    private int y;
    public Legal() {
        y=0;
    }
    public Legal(String x) {
        this();
        System.out.println("legal constructor worked: "+x);
    }
}

class Illegal extends RequiresDefaultConstructor {
    public Illegal(String x) {}
}

Output:
legal constructor worked: hi
Exception in thread "main" java.lang.ExceptionInInitializerError
        at java.lang.Class.forName0(Native Method)
        at java.lang.Class.forName(Unknown Source)
        at RequiresDefaultConstructor.main(RequiresDefaultConstructor.aj:17)
Caused by: java.lang.IllegalStateException: class class Illegalwithout default c
onstructor
        at EnforceRequiresDefaultConstructor.ajc$afterReturning$EnforceRequiresD
efaultConstructor$30(RequiresDefaultConstructor.aj:7)
        at Illegal.<clinit>(RequiresDefaultConstructor.aj)
        ... 3 more

Ron

Ron Bodkin
Chief Technology Officer
New Aspects of Software
o: (415) 824-4690
m: (415) 509-2895

> ------------Original Message------------
> From: "JITESH KALYANI Shivanand" <SJitesh@xxxxxxxxxxxx>
> To: <aspectj-users@xxxxxxxxxxx>
> Date: Fri, Mar-26-2004 11:45 AM
> Subject: RE: [aspectj-users] Declare error
> 
> HI,
> 
> I have tried small example. We can have poincut to constructor and check if it is default constructor OR prameterised constructor. If it is prameterised constructor, throw error. See if this u want.
> 
> 
> class constructorTest  
> {	
> 	int a = 0;
> 
> 	public static void main(String[] args) 
> 	{
> 		constructorTest  obj1 = new constructorTest();  
> 		constructorTest  obj2 = new constructorTest(10);
> 		System.out.println("Program Over!");
> 	}
> 	
> 	public constructorTest() {
> 		System.out.println("Executing Default Constructor");
> 	}
> 	
> 	public constructorTest(int a) {
> 		this.a = a;
> 		System.out.println("Executing parameterised Constructor : a = "+a);
> 	}
> }
> 
> 
> aspect testaspect
> {
> 	pointcut myConstructor() : within(constructorTest) && execution(constructorTest+.new(..));
> 
> 	 before (): myConstructor() {
> 		 Object[] args = thisJoinPoint.getArgs();
>         		if(args.length == 0) {
> 			System.out.println("Default Constructor");
> 		}else {
> 			System.out.println("Parameterised Constructor");
> 			//throw error.
> 		}
> 	}
> }
> 
> Jitesh
> 
> 
> 
> > ----------
> > From: 	aspectj-users-admin@xxxxxxxxxxx[SMTP:aspectj-users-admin@xxxxxxxxxxx] on behalf of André Dantas Rocha[SMTP:ad-rocha@xxxxxxxxxx]
> > Reply To: 	aspectj-users@xxxxxxxxxxx
> > Sent: 	Friday, March 26, 2004 5:17 PM
> > To: 	aspectj-users@xxxxxxxxxxx
> > Subject: 	RES: [aspectj-users] Declare error
> > 
> > I don't know how to....
> > 
> >   _____  
> > 
> > De: aspectj-users-admin@xxxxxxxxxxx [mailto:aspectj-users-admin@xxxxxxxxxxx] Em nome de Nicholas Lesiecki
> > Enviada em: sexta-feira, 26 de março de 2004 01:51
> > Para: aspectj-users@xxxxxxxxxxx
> > Assunto: Re: [aspectj-users] Declare error
> > 
> > 
> > Possibly. Can you write an attempt at doing this and submit it to the list?
> > 
> > Nick
> > On Mar 25, 2004, at 12:53 PM, André Dantas Rocha wrote:
> > 
> > 
> > 
> > Hi,
> >  
> > I would like to declare an error if any subtype of ClassA do not have a default constructor.
> > Is it possible?
> >  
> > Thanks
> > 
> > 
> > 
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