Does it make sense to remove slots ?

[Massimo Dentico]

Todd Fleming wrote:


> Massimo Dentico wrote:
> 
>> Tim Moore wrote:
>>
>>> Long story short: Todd is right. Circle shouldn't be derived from 
>>> Ellipse unless they're both immutable, and most likely you don't 
>>> really need a Circle type at all.
>>
>>
>> Please, explain what does it mean to mutate a *value*.
> 
> 
> I think we're talking about objects, not values.

Sorry, the term "object" is so confused and overloaded that for
a moment I forgot its meaning in Slate.


> The squishing problem still exists whether Circle is a 
> subtype of Ellipse or it inherits from Ellipse, except if
> they are treated as immutable.

Well, I remember that in the series of articles by Chris Date
pointed out by me, "WHAT DOES SUBSTITUTABILITY REALLY MEAN?"

    http://www.dbdebunk.com/page/page/626998.htm

he addressed precisely this problem and propose his and Hugh Darwen
"inheritance model":

    And we would really like to suggest, with all due respect,
    that the industry leaders in this field, instead of spending
    so much time and effort in trying to persuade the rest of us
    that squares aren't rectangles and circles aren't ellipses,
    would take a look at our model and see how we do it!

Unfortunately I don't remember the details, I need to re-read it.

Regards.

--
Massimo Dentico