Re: class wide iterable (and indexable)

["Jeffrey R. Carter" <spam.jrcarter.not@spam.not.acm.org>]

On 1/5/19 10:09 PM, Shark8 wrote:
> 
> Hm, I'm not sure I agree with you -- plug-ins seem to be a counter-example in that they *are* extensions [of the base program] -- it seems a bit excessive to think that any program that uses/handles plug-ins is ill-designed and by-nature violative of good SW engineering.

I don't think plug-ins qualify as programming by extension, since they don't 
involve extending an existing type (I'm not very familiar with how plug-ins are 
written for things that allow them, so I may be mistaken).

But I'm not sure that allowing plug-ins is good S/W eng. The goals of S/W eng 
are S/W that is correct, reliable, robust, and easy to understand and modify. 
How do you ensure that if you allow any coder to write a plug-in?

> Of course this is an interesting observation in its own right, and I should like to hear more.

My observations about programming by extension are in the /Ada Letters/ articles 
"Ada's Design Goals and Object-Oriented Programming", "Breaking the Ada Privacy 
Act", and "OOP vs. Readability", available at

http://pragmada.x10hosting.com/papers.html

These are over 20 years old. The 1st and last deal with type extension and the 
2nd with child pkgs that extend their ancestor(s). The type-extension examples I 
cite do not use child pkgs, perhaps because both were new concepts in Ada and 
the authors did not want to confuse readers with an extra new concept, but I 
don't think revising them to use child pkgs would change anything.

-- 
Jeff Carter
"Now look, Col. Batguano, if that really is your name."
Dr. Strangelove
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