Re: Howto declare an Ada container with access to objects of a class hierachy

[Thomas Schmidt <tc.schmidt@gmx.net>]

Adam Beneschan <adam@irvine.com> wrote:
> [Sorry if this is a double post.  Google is being obstinate.]
> 
> On Wednesday, June 12, 2013 5:43:22 PM UTC-7, Thomas Schmidt wrote:
> 
>> Hi,
>> 
>> Hoping this Is the right newsgroup for asking my question. 
> 
> Yes, it is.  Welcome.
>  
>> I want to set up a hashed set of accesses (allocated from heap) to objects 
>> of a given class hierarchie (the top class may f.e. be called "Top"). I 
>> decided to use "Ada.Containers.Indefinite_Hashed_Sets". The hash method 
>> should be a primitive which may be overwritten by derived classes. I've 
>> declared Tops hash functions formal parameter as of type "access Top". How 
>> do I've to declare the sets Element_Type? I think if I use "Top'Access" it 
>> wouldn't fit the hash functions 
>> parameter type nor could I store objects of classes derived from "Top". 
> 
> First of all: I'm assuming that when you want a set of "accesses to
> objects", you really mean that you want to work with your own accesses
> (Ada's term for pointer), and you're going to allocate them yourself
> with a "new" operator.  
> [...]
> I realize this is a bit complicated.  Hope this helps,
> 
>                              -- Adam

Thank you very much! Your tips and hints are very precise and helped a lot.
Now everything is running as I've expected.

Thomas