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From: "Samuel T. Harris" <u61783@gsde.hou.us.ray.com>
Newsgroups: comp.lang.ada
Subject: Re: Stream_Element_Array and an empty array
Date: Thu, 23 Aug 2001 09:02:17 -0500
Organization: Raytheon Aerospace Engineering Services
Message-ID: <3B850CE9.DCC6533D@gsde.hou.us.ray.com>
References: <pan.2001.08.22.15.34.27.59.13195@zamek.gda.pl>
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Xref: archiver1.google.com comp.lang.ada:12327
Date: 2001-08-23T09:02:17-05:00
List-Id: <comp.lang.ada>

Philip Anderson wrote:
> 
> "Samuel T. Harris" wrote:
> >
> <snip>
> > Given that in the above text A is a variable,
> > no assignment is necesary. If you must have
> > an assignment, or an initial expression
> > because it is constant, then you can
> > do the following ...
> >
> > nil : constant stream_element_array (1..0) := (others => 0);
> > ...
> > a := nil;
> 
> That must the clearest Ada way of obtaining a zero-length array of a
> particular type; declare an example and give it a suitable name (Nil,
> Empty_Array, Zero_Length_Array, whatever), since the result of this
> particular Ada idiom is easier to understand given this clue.  It then
> becomes obvious what you are doing when you pass it as a parameter.
> 

Thanks for that.

For years (decades) I have made is a habit to always
define a nil constant for any interesting type.
Even my record types, whose every field declaration
has a default initial expression, also gets a nil_type
constant.

Along those lines, I also define width, image, and value
functions so I get easy instrumentation or I/O facilities
nearly for free.

-- 
Samuel T. Harris, Senior Software Engineer II
Raytheon, Aerospace Engineering Services
"If you can make it, We can fake it!"