2015-06-30 11:30 GMT+02:00 Tudor Girba <tudor@tudorgirba.com>:
What he means is that just because subclassing is available as a technical mechanism, we should only use it for modeling subtyping and not implementation reuse (only in very few cases this is actually useful in the long run).
Given how Smalltalk defines types and subtyping, I consider that subclassing should be used for implementation reuse and not for subtyping. Any Smalltalk class hierarchy which has instance variables defined in the superclass does implementation sharing/reuse. Modeling is another consideration. (I still consider the meaning of Stef phrase confusing...)
For reference, this goes under the name of Liskov substitution principle and one nice article that explains it is this one: http://www.objectmentor.com/resources/articles/lsp.pdf
This reference is too much into how that particular principle turns out in an ill-designed type and code sharing mechanism (C++) to be of much help ;) Thierry
Cheers, Doru
On Tue, Jun 30, 2015 at 11:21 AM, Thierry Goubier < thierry.goubier@gmail.com> wrote:
2015-06-30 11:00 GMT+02:00 stepharo <stepharo@free.fr>:
What I mean is that this is not good to have subclassing when we can use subclassing.
Are you sure you mean that? *confused*
Thierry
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