anonymous array types and record components

anonymous array types and record components

[Doug Bryan]

Hi all...

One of my students asked me a question the other day that I could not
answer.  Since this does not happen too often, I got out a few reference
books and started digging.  I still don't have a good answer!  Here is
the question...

	X : array (1 .. 10) of Integer;

Using an anonymous array type for an object declaration is valid.

	type R is record
	    X : array (1 .. 10) of Integer;
	  end record;

Using an anonymous array type for the component of a record is invalid.
Why?  What is the rational for disallowing anonymous array types
for record components?

Any hints would be appreciated.

doug bryan
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Re: anonymous array types and record components

[jankok]

In article <8602120210.AA01239@ucbvax.berkeley.edu> info-ada@ucbvax.UUCP writes:
>the question...
>
>	X : array (1 .. 10) of Integer;
>
>Using an anonymous array type for an object declaration is valid.
>
>	type R is record
>	    X : array (1 .. 10) of Integer;
>	  end record;
>
>Using an anonymous array type for the component of a record is invalid.
>Why?  What is the rational for disallowing anonymous array types
>for record components?

The possibility to declare anonymous array types inside a
record types was only removed in a very late stage of the 
Ada language development, it was still present in the 1980
definition.
The following justification is not mine and I do not say that
it clears the question completely. I quote from a paper 
distributed at the Ada-Europe 1982 Conference (joint with AdaTEC)
held in Brussels (you all know now that 's in Belgium). It is
"Summary of language changes" by Ben Brosgol:
    To avoid the semantic complexities of nested type definitions,
    array type definitions may no longer be used in the declaration
    of record components.  (A named array type must be explicitly
    introduced by the programmer instead.)
-- 
jan kok, cwi (afd. nw), amsterdam, nederland
UUCP: {seismo, decvax, philabs, okstate, garfield}!mcvax!zuring!jankok
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