Re: Containers - nontrivial element access

[Maciej Sobczak <see.my.homepage@gmail.com>]

On 2 Pa , 18:37, Matthew Heaney <mhea...@on2.com> wrote:

> V : Person_Vectors.Vector;
>
> declare
>    procedure Process_X (PX : in out Person) is
>       procedure Process_Y (PY : in out Person) is
>          SX : constant Salary_Type := PX.Salary;
>       begin
>          PX.Salary := PY.Salary;
>          PY.Salary := SX;
>       end;
>    begin
>       V.Update_Element (Y, Process_Y'Access);
>    end;
> begin
>    V.Update_Element (X, Process_X'Access);
> end;

I have mixed feelings about this example.

I like it, because it solves the problem without requiring any
additional variable.
I don't like it, because it imposes some artificial assymetry (one of
the procedures has to be nested) where the problem is strictly
symmetrical.

OK, this assymetry stuff is nit-picking. I accept this as a valid
solution, even though it is not even close in readability to my
initial C++ example.

BTW - above, PX plays the role of that additional variable that is
sneaked around to the second procedure. Here it just pretends to not
exist by taking the form of a parameter in the outer procedure. I
don't think there is a reasonable way to avoid it.

--
Maciej Sobczak * www.msobczak.com * www.inspirel.com