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From: tmoran@acm.org
Newsgroups: comp.lang.ada
Subject: Re: Direct_IO problem -- generic package problem
References: <3B4DD722.EB6F3AB7@boeing.com>
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Date: Thu, 12 Jul 2001 19:23:44 GMT
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>Instantiate Direct_IO with constrained subtypes of Matrix for the types
>of interest.
i.e.
>My own ideas is to create separate databases for all eight databases
>that uses DB (CAR_DB, BOAT_DB, HOUSE_DB...) with specified values for
>MATRIX, but that seems like a lot of work and not very objectoriented.
  If you are doing direct IO all the records in a given file need to
be the same size anyway, so it certainly is reasonable to instantiate
Ada.Direct_IO once for each of the eight database files.  Did the
old program actually mix different size records in a single file?  How
did it know where to look for record N?  As for OO, if you have a
root Matrix tagged type make it abstract, then each of the eight
children should have its own overide of its input/output routines
using the appropriate instantiation.