Re: Variant record limitation - what's a better solution?

[Eryndlia Mavourneen <eryndlia@gmail.com>]

On Tuesday, July 9, 2013 1:38:09 AM UTC-5, Peter Brooks wrote:
> Peter Brooks <peter.h.m.brooks@gmail.com> wrote:
> 
> I'm still having trouble with this. I've tried using functions, as suggested, but it doesn't allow overloaded functions in the varient part. Here's what I tried:
> 
> "
> type
> small_lorry_load is new integer range 1..2;
> type
> medium_lorry_load is new integer range 1..18;
> type
> large_lorry_load is new integer range 1..36;
> type
> all_lorry_loads is new integer range 1..36;
> 
> type
> lorry_size is (small,medium,large);
> 
> type
> lorry_type(lorry : lorry_size) is
>         record
>                 number_plate : lorry_number_plate;
>                 location : depot_name_type;
>                 destination : depot_name_type;
>                 case lorry is
>                         when small => lorry_load : load(lorry);
>                         when medium => lorry_load : load(lorry);
>                         when large => lorry_load : load(lorry)
>                 end case;
>         end record; 
> "
> 
> I know that the syntax is wrong - I've been trying all sorts of alternatives. What have I not understood?

As a point of instruction, the Lorry_Load types also could be defined like this:

   type    All_Lorry_Loads   is range 1..36;
   subtype Small_Lorry_Load  is All_Lorry_Loads range 1..2;
   subtype Medium_Lorry_Load is All_Lorry_Loads range 1..18;
   subtype Large_Lorry_Load  is All_Lorry_Loads range 1..36;

which will make all the Lorry_Load types directly interrelated, thereby making the job of the programmer easier.  The definition of All_Lorry_Loads also allows the compiler to choose the exact representation of the integers.