Re: API design considerations - variable-length array in record type

[Shark8 <onewingedshark@gmail.com>]

On Monday, October 8, 2012 3:03:04 AM UTC-6, Maciej Sobczak wrote:
> 
> type R is record
>    X : Integer;
>    Y : Unbounded_String;
>    Z : Array_Of_Integers_That_We_Talk_About_Here;
> end record;
> 
> Requirements:
> 1 - the enclosing record type should not be limited (it should be copyable)
> 2 - the record type can be explicitly controlled, if necessary
> 3 - the record type should be definite (it should not require initialization)
> 4 - it should be possible to assign to Z, just as it is possible to assign to X and Y, and the new value for Z *might have a different length* 

Why not use discriminants on the record?

Default : Constant := Natural'First;
type R( Array_Length : Natural:= Natural'First ) is record
   X : Integer;
   Y : Unbounded_String;
   Z : Array_Of_Integers_That_We_Talk_About_Here(1..Array_Length):= (Others => Default);
end record;