Re: [abc-users] Compilation error with intertypes when using the abc weaver

Hi Eric,

Thanks for taking the time to look into this.

I was intrigued by your diagnosis, so I consulted the Java Language
Specification. The relevant section is:

http://java.sun.com/docs/books/jls/third_edition/html/lexical.html#3.8

This states, among other interesting and useful things,

"The Java letters include uppercase and lowercase ASCII Latin letters A-Z
(\u0041-\u005a), and a-z (\u0061-\u007a), and, for historical reasons, the
ASCII underscore (_, or \u005f) and dollar sign ($, or \u0024). The $
character should be used only in mechanically generated source code or,
rarely, to access preexisting names on legacy systems."

The $ character is perfectly legal in Java identifiers (in fact you can have a
variable called "$"), but is usually omitted from introductory texts because
it is used for compiler-generated names (cf. this$0, names for nested classes,
accessor methods and advice names) and if human programmers avoid it, the
probability of accidental name clashes is reduced.

- P

On Tuesday 19 May 2009 12:28:34 Eric Bodden wrote:
> > Yes, surprisingly both alow that. In relation to Java, I first saw
> > such a situation in the instrumented source code
> > generated by JML. In addition, since a valid AspectJ program is also
> > a valid Java program, we can use "$" in AspectJ
> > programs as well, for instance, in intertype declarations (as in
> > previous email).
>
> Yes, there's two different things: identifiers in Java source code and
> identifiers in the bytecode. $ is allowed in bytecode but not usually
> on the source level. The AspectJ language definition states that
> AspectJ identifiers are just Java identifiers. Therefore AspectJ
> compilers should not actually parse your example program. I have
> raised a bug against ajc to clarify that...
> https://bugs.eclipse.org/bugs/show_bug.cgi?id=276794
>
> Anyway, I have not yet had the time to look into this but I suspect
> that abc may get confused by those names. I will see if I can find
> some time to dig a bit deeper into the problem today.
>
> Eric
Received on Tue May 19 2009 - 12:46:08 BST