Re: Spark's class analysis

[Ondrej Lhotak <olhotak@sable.mcgill.ca>]

This depends on the option settings.

If on-fly-cg is false, a class hierarchy analysis is used to build a
call graph before Spark starts. This means that it looks at the declared
type of o, which is C, and assumes that o could be any subtype of C
(namely A, B, C), and therefore the call could go to any of the three
m() methods.

If on-fly-cg is true, Spark uses the points-to information it computes
to build the call graph as it runs. In this case, after seeing the
statements o = new B(); and o = new A();, it knows that o could have
type A or B, and the call could therefore go to either A.m() or B.m().

Ondrej

On Wed, Jul 16, 2003 at 11:09:45AM +0200, Christophe Massol wrote:
> Hello,
> 
> 	Does Spark perform a Class analysis to know the possibles methods to call in 
> this exemple : (o.m() )
> 
> 
> public class Test{
> 	C o;
> 
> 	public Test(String bool){
> 		if(bool.equals("true")){
> 			o = new B();
> 		}
> 		else{
> 			o = new A();
> 		}
> 		o.m();
> 	}
> 
> 	public static void main(String[] argv){
> 		new Test(argv[0]);
> 	}
> 
> 	public Object[] get(){
> 		return new Object[3];
> 	}
> 
> }
> class C {
> public void m(){
> }
> }
> 
> class B extends C {
> public void m(){
> }
> }
> class A extends C {
> public void m(){
> }
> }
> -- 
> 
> Cordialement,
> 
> 	Massol Christophe
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