Re: Function definitions - with clarification

[Adam Beneschan <adambeneschan@gmail.com>]

On Sunday, June 22, 2014 4:34:09 AM UTC-7, montgrimpulo wrote:

> type Individual (P, Q, R) is record 
> X : x_array (0..P); 
> Y : y_array (0..Q); 
> Z : z_array (0..R); 
> end record; 

> -- type population is array (1 .. Popsize) of Individual; 
> -- gives: unconstrained element in array declaration 

If you are trying to set up an array of Individuals where the Individuals could all have different discriminants: you can't do that in Ada.  Sorry.  The reason is that to set up an array, the elements all have to be the same size, and an Individual(P=>3, Q=>5, R=>4) will have a different size than an Individual(P=>2, Q=>2, R=>1).  [That may not be true on all compilers.  But the language was designed so that it would work on compilers that do allocate different sizes for those different records.]

If this is what you want, you will have to start using access types.  I.e.

    type Individual_Acc is access Individual;
    type population is array (1 .. Popsize) of Individual_Acc;

Now, all the array elements are accesses (pointers), so they will have the same size.

If you want a Population where each Individual has the **same** discriminants, you could get it to work by putting discriminants on the array.  The problem is that you can't put discriminants on an array, but you can put them on a record containing the array:

    type Population (P, Q, R : Natural) is record
        Population_Data : array (1 .. Popsize) of Individual(P, Q, R);
    end record;

I haven't tested this but I *think* it will work.

                           -- Adam