Re: Addressing functions

[mfeldman@seas.gwu.edu (Michael Feldman)]

In article <3citrc$bb5@earth.usa.net>, Bill Buckley <wbuckley@earth> wrote:
> 
>High Ada lovers, I've got a question on storing subprogram address in 
>Ada.  I know I can get the address of a subprogram via the ADDRESS 
>attribute in Ada but can not figure a way to use it.  I don't have any 
>immediate need for such a procedure but it has my old C-C++ courisity 
>wondering.  For instance if I were to have an array of subprogram addresses
>A(1..2) => (1 => Print1'ADDRESS,
>            2 => Print2'ADDRESS);
>how could I implement the calling these functions (note : I know the 
>syntax above is wrong but can't get this simple editor to back up to 
>change it).  I have heard from several other Ada programmers that this 
>may not be possible. 

You can usually get something reasonably meaningful by casting the address
to an integer. Instantiate Unchecked_Conversion: 

FUNCTION AddressToInt IS NEW Unchecked_Conversion 
  (Source => System.Address, Target => Integer);

you can then use a normal Integer_IO instance to display it. If the
instance is called My_Int_IO, then

   My_Int_IO.Put(Item => AddressToInt(Print1'Address), Base => 16);

should display it nicely in hexadecimal.

Mike Feldman