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From Jochen Theodorou <>
Subject Re: Synthetic GroovyObject methods
Date Fri, 09 Mar 2018 23:10:20 GMT
On 09.03.2018 17:19, Daniel.Sun wrote:
> Hi Daniil,
>        Maybe Jochen can tell us the reason.
>        Ping Jochen ;-)

Checking Verifier I see:

>         if (!node.hasMethod("getProperty", GET_PROPERTY_PARAMS)) {
>             MethodNode methodNode = addMethod(node, !isAbstract(node.getModifiers()),
>                     "getProperty",
>                     ACC_PUBLIC,
>                     ClassHelper.OBJECT_TYPE,
>                     GET_PROPERTY_PARAMS,
>                     ClassNode.EMPTY_ARRAY,
>                     new BytecodeSequence(new BytecodeInstruction() {
>                         public void visit(MethodVisitor mv) {
>                         }
>                     })
>             );
>             if (shouldAnnotate) methodNode.addAnnotation(generatedAnnotation);
>         }

This is having only ACC_PUBLIC as modifier, no ACC_SYNTHETIC.

Using Groovy 2.4.14 to compile class X{} shows this:

>   // access flags 0x1001
>   public synthetic getProperty(Ljava/lang/String;)Ljava/lang/Object;

Investigating further shows, addMethod is there as well.... 
investigating more into the history points me to

> fix for GROOVY-3877. To ensure abstract classes can always be extended in Java, even
if precompiled, all Groovyobject methods must not have the synthetic flag being set. In normal
classes this is no problem.

but that is only to lift the restriction for abstract classes.... and 
then it goes to way before... 891ad59d074990a38d7ba0dca65890e80061158a 
from Jan 29 2004, a change made by James explicitly to add synthetic

I think the idea was that everything the compiler adds as a helper 
method is supposed to be synthetic. Most likely back then getProperty 
and friends have been seen as internal methods, not to be called 
directly. And from Java code you rarely do. In most cases you go through 
GroovyObject instead. Now given that this is there for like 14 years I 
think it is worth spending a minute on the implications.

In an IDE, if you have x.<auto complete keys here> you would then be 
presented with getProperty, setProperty and get/setMetaClass. Do we 
actually want that?

bye Jochen

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