Re: Question about record rep spec placement

[Jerome Desquilbet <jDesquilbet@Rational.COM>]

Ken Garlington wrote:
> 
> We have some Ada83 code that looks like the following:
> 
> package Some_Package is
> 
>   type Some_Record is record
>    -- components here
>   end record;
> 
>   -- some arbitrary declarations here
> 
> private
> 
>   for Some_Record use record
>    -- component rep spec here
>   end record;
> 
> end;
> 

[...]

> when this code was compiled with an Ada 95 compiler, that the record
> rep spec had to be moved to immediately after the record declaration
> for the code to compile correctly.

This kind of contruction is legal in Ada 83 and in Ada 95.

And I think this is really good style: you may want to hide in a private
part the implementation details.

The following example compiles with my Ada 83 and Ada 95 compilers:


with System;
package Communication is
    type Date is range 0 .. 3600;
    type Word is range -(2 ** 31) .. (2 ** 31) - 1;

    type Message is
	record
	    Send_Date : Date;
	    Content : Word;
	end record;
private
    for Date'Size use 16;
    for Word'Size use 32;
    for Message use
	record
	    Send_Date at 0 range 0 .. Date'Size - 1;
	    Content at (Date'Size / System.Storage_Unit)
	       range 0 .. Word'Size - 1;
	end record;
    for Message'Size use Date'Size + Word'Size;
end Communication;


You are able to document this as:


with System;
package Communication is
    type Date is range 0 .. 3600;
    type Word is range -(2 ** 31) .. (2 ** 31) - 1;

    type Message is
	record
	    Send_Date : Date;
	    Content : Word;
	end record;
private
    ...
end Communication;

______________________________________________________________________
Jerome Desquilbet                             jDesquilbet@Rational.COM
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