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From: Niklas Holsti <niklas.holsti@tidorum.invalid>
Newsgroups: comp.lang.ada
Subject: Re: 'Protected' abstract subprograms
Date: Sat, 11 Jan 2014 15:42:39 +0200
Organization: Tidorum Ltd
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Date: 2014-01-11T15:42:39+02:00
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On 14-01-11 10:59 , Dmitry A. Kazakov wrote:

> First, and foremost, never re-dispatch, that is semantically broken [*],

Not all of us agree with that, and I'm one of them. (I'm just adding a
note to this conversation; I'm not trying to reopen our earlier
discussion on this point with Dmitry, which did not lead anywhere.)

> potentially unmaintainable (due to substitutability hell) and inefficient
> too.

I've had no such problems.

> * When you dispatch in a body of an operation that means that the body is
> valid for more than one type. Many types = class. Operation for all class =
> class-wide operation.

Yes, but "many types" is not the same as "all class". I find it useful
to have primitive operations that implement some behaviour that is not
class-wide, because some types in the class need to alter (override) the
behaviour, yet these operations depend on type-specific lower-level
behaviour, and therefore they call primitive operations with redispatch.

> Re-dispatch breaks this model and effectively makes your design
> un/weakly typed.

I don't agree, because my conceptual "model" is different. Your model is
stronger (more specific) than mine, which paradoxically means that it is
easier to break :-)

-- 
Niklas Holsti
Tidorum Ltd
niklas holsti tidorum fi
      .      @       .