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From: "Jeffrey Creem" <jeff@thecreems.com>
Newsgroups: comp.lang.ada
References: <3DAFC542.152C0EE0@lml.ls.fi.upm.es>
 <Xns92AB77A045543BerndSpechtgmxcom@139.25.208.17>
 <slrnaqvosa.nv.lutz@taranis.iks-jena.de>
Subject: Re: Porting from Modula-2 to Ada
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Xref: archiver1.google.com comp.lang.ada:29897
Date: 2002-10-18T10:55:33+00:00
List-Id: <comp.lang.ada>

I'd probably go with a generic that can be instantiated for each "thing" you
want to
write or use a ugly 'address and 'size based approach that does not require
generics.
Note that if you take the generic route it is a little more work but
somewhat cleaner.

When I have done this I tend to make the generic formal parameter be private
instead
of limited private. There are times when limited might be right but almost
any time
someone makes something limited, the in memory representation one would get
via the
type is somewhat bogus.

Also, it is worth checking in the generic body that the 'size of the type is
a multiple of
the 'size of the storage element (or whatever type you use to write to the
file)

"Lutz Donnerhacke" <lutz@iks-jena.de> wrote in message
news:slrnaqvosa.nv.lutz@taranis.iks-jena.de...
> * Bernd Specht wrote:
> > Would it be an idea not to substitute the procedure by _one_ other
> > procedure but with a set of overloaded procedures?
> >
> > procedure Xxx (raw : Integer_Field) is ...
> > procedure Xxx (raw : Character_Field) is ...
> > procedure Xxx (raw : Float_Field) is ...
>
> And now use generics:
>
> generic
>   type T(<>) is limited private;
> procedure Xxx (data : T);
>
> procedure Xxx (data : T) is
>   use System.Storage_Elements;
>   raw : Storage_Array (Storage_Offset'First ..
>         Storage_Offset'First + (data'Size + Storage_Unit - 1) /
Storage_Unit);
>   pragma Import (Ada, raw);
>   for raw'Address use data'Address;
> begin
>   ...