[Grace-core] Abstract methods/classes

[PSU via GMail]

Andrew P Black

> On 4 Jun 2014, at 03:15, Timothy Jones <tim at ecs.vuw.ac.nz> wrote:
> 
> I'm leaning back to the annotation approach, where it just bans you from calling
> it directly, but allows you to call it through super or inherit from it. That
> way it works for both methods and class methods.

I don't think that I understand this remark.  What does "calling it directly" mean?   Requesting an abstract method on self?  Being able to write such a request is the while reason for having abstract methods.

In the dynamic semantics, an abstract method is not there — and requesting it will give a "method does not exist" error.    Because the method is not there, I would prefer an annotation (perhaps is required rather than is abstract) to a body. 

In the same meeting that James referred to, we also disused an "is complete" annotation on an object that invites a checker to check that an object actually defines all of the methods that it self-requests.  We should not make that test the default, because it will upset the people who like to do dynamic programming.  

       Andrew

       
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