[JSR308] Constructor Annotation Inference

Niko Matsakis niko at alum.mit.edu
Thu Jan 15 11:51:34 EST 2009


Unfortunately, I haven't been able to work on my JSR308 project for a  
while.  However, I am back at work and therefore have a few more  
questions about the framework. :)

I am attempting add some code that infers the correct annotations on  
constructors based on the types of their arguments.  In my  
AnnotatedTypeFactory, I overloaded constructorFromUse() to do the  
correct inference and that seems to work correctly.  However, I run  
into some problems because the result of that method does not seem to  
be connected to the type of a NewClassTree as computed by  

I had expected that fromExpression() would eventually invoke  
constructorFromUse() to get the correct constructor signature, and use  
that to compute the resulting type of the NewClassTree, but I see that  
is not the case.  Moreover, thinking about it more, I'm not sure if  
that makes sense anyhow-- as it happens, in my case the receiver in  
the constructor's executable type is the same as the result from the  
NewClassTree, but I suppose that is not necessarily the case.

In any case, where is the right place to overload so as to affect the  
type which fromExpression() returns for a NewClassTree?  Looking at  
the code, I see no obvious hook apart from overloading  
fromExpression() altogether.

As a side comment: I think that the use of static visitors in the  
AnnotatedTypeFactory inhibits reuse, because there is no easy way for  
a subtype to customize the content of those visitors.  It would be  
better to have a factory method like:

class AnnotatedTypeFactory {
	class SomeVisitorClass extends TypeVisitor {
	public TypeVisitor someVisitorClassInstance() {
		return new SomeVisitorClass();

then a subclass could overload someVisitorClassInstance().  If  
efficiency is a concern, then the result of that method could be cached.


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