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Re: Can someone explain?
-
Pierre Weis
-
skaller
- Jerome Vouillon
- Gerd Stolpmann
- Lyn A Headley
-
skaller
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| Date: | -- (:) |
| From: | Jerome Vouillon <vouillon@p...> |
| Subject: | Re: Can someone explain? |
On Tue, Oct 05, 1999 at 08:57:20AM +1000, skaller wrote: > Pierre Weis wrote: > > > > > Is there a way to access a value of a class instance? > > > If so, what is the syntax? If not, what is the purpose > > > of allowing 'val' bindings in class declarations in module > > > signatures? > > > > The only way to access a value of a class instance is via method > > invocation: you have to define a method that returns the value. > > Thanks, but you have not answered the real question here: > WHY are the values present in the interface when they are not accessible > via the interface? > > > > Similarly, what is the purpose of allowing 'virtual' > > > methods in class types and class declarations in > > > module signatures? > > > > Virtual methods are methods that are declared but not implemented: > > sub-classes must define them. > > Again, I knew that, the real question is WHY this information > is in the _interface_?? This information is in the interface because a class declaration can also be used for inheritance, and a subclass can access the instance variables of its parent and provide an implementation for the virtual methods. -- Jérôme