[Grace-core] Super-Outer-Objects: What does your language (gBeta/Newspeak/Scala/Java…) do with this? What should Grace do?

[Andrew P. Black]

On 19 Nov 2012, at 2:26, James Noble wrote:

> What do other languages do?     What should Grace do?  

I'll add some line numbers of reese of reference.


> 1.   #pragma DefaultVisibility=public
> 
> 3.   def A = object {
> 4.       method pathological {print "A-pathological"}  
> 5.       def B = object {
> 6.            method foo {pathological}
> 7. 	   }
> 8.   }
> 
> 10.  def C = object { 
> 11.            inherits A.B
> 12.            method pathological {print "C-pathological"}
> 13.   }
> 
> 15.  A.pathological
> 16.  A.B.foo
> 17.  C.pathological
> 18.  C.foo

Here's what I think Grace should do, and why.

The "receiverless"   request pathological on line 6 is potentially ambiguous: it might mean self.pathological, or it might mean A.pathological (or, outer.pathological, depending on whether A is in scope inside the definition of A, which is a separate issue.)  In this case the ambiguity is easy to resolve; it can't mean self.pathological, because there is no method pathological in B, so it must mean A.pathological.

Hence, line 15 and 16 both print "A-pathological".

When object C inherits A.B on line 11, it gets the method foo (only) from B.   (A has an auto-generated method B because of the  #pragma DefaultVisibility=public; this seems to be irrelevant to the example, since B could just as well be declared as a method directly, but perhaps James will explain why he did it this way.)   On line 12, object C is also given its own method pathological; not that this is not an override, but a new method.

So C.pathological prints "C-pathological", whereas C.foo requests the foo method on line 6, which in turn requests A.pathological, which prints 
"A-pathological".


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