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From: Ehud Lamm <mslamm@mscc.huji.ac.il>
Subject: Re: OO puzzle
Date: 1999/12/25
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In article <83uk4d$mec$1@nntp6.atl.mindspring.net>,
  swhalen@netcom.com wrote:
>
> I'm missing something here (which is not that unusual <g>).
>
> I know Ada _much_ better than I know Eiffel, but my impression is
> that Ada already _is_ designed
>
>     "in such a way as to ensure as much can be done during compile
>      time, as possible without hurting expressablity to much."
>
> In many ways, that seems to me a good definition of one of the major
> design goals (and successes) of Ada.
>

Quite. But in this case we are talking about something very specific,
so the question is could this specific kind of checks be done before
runtime, and at what costs.

Compare this with generics. Ada(83) generics are designed so that
checking can be done seperately on the generic unit, and the
instantiation. This allow seperate compilation, and early detection of
errors. But it relies on the fact the generic paramaters compromise
very specific classes of types etc.

OO which by nature uses late binding etc. can make this issue harder.

One more reason why I am a fan of generics.

But still not an answer to the specific cases I outlined in the
original post. Can we ensure the truck_driver/driver distinction using
compile time checks?

--
Ehud Lamm mslamm@mscc.huji.ac.il
http://purl.oclc.org/NET/ehudlamm
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