Re: Can someone explain?

[Jerome Vouillon <vouillon@pauillac.inria.fr>]

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