try catch in NewExpr

[vladsk]

Actualy I wanted to catch exceptions in during Object creation
So I did:

public class NewCodeConverter extends ExprEditor {

public void edit(NewExpr expr) throws CannotCompileException {
StringBuffer code = new StringBuffer(300);
code.append("{ try ");
code.append("{ $_ = $proceed($$); }");
code.append("catch (OutOfMemoryErrore) {...} }");
expr.replace(code.toString());
}
}

but during execution I get:
Exception in thread "main" java.lang.VerifyError:
method: my_getmem signature: (I)V) Inconsistent stack height 0 != 2

could you help?
Regards,
VladS
Also are thre a bugs database?

[chiba]

The reason of that exception is that $_ is not initialized if an OutOfMemoryError exception is thrown.
So the problem should be fixed if you assign some value to $_ in the catch block.

I have also modified Javassist so that $_ is automatically initialized. If you use Javassist directly downloaded from the CVS head (or use an upcoming beta 3 or later), your code above should run without any problem.

[vladsk]

During last week I made instrumentaton of a large project.
And some time I have seen java.lang.VerifyError at run time.
Is it posible to run code verification before saving class file?

[chiba]

Currently, no.
I'm putting error checking code to avoid
wrong instrumentation, but it is not a simple
thing to produce useful error messages.

Also, I have to consider the range of possible
instrumentation. For example, changing
a public method to be private would cause
VerifyError if some methods in another
class access that method. Detecting this
error before saving a class file is a complicated
task under the current architecture of Javassist.

It would be great if you give me back your
experiences of VerifyError. I can improve
erorr checking code.