default generic parameter ?

default generic parameter ?

[Bini]

generic
	type Item is private;
	with procedure Item_Destroy(I : out Item) := null; -- Invalid syntax...
package List is
	type List is limited private;
	type List_Element is limited private;
	.
	.
	. -- procedure and function for List ...
	.
private
	type List_Element_Record;
	type List_Element is access List_Element_Record;
	type List_Element_Record is record
		Data	: Item_T;
		Next	: List_Element := null;
	end record;

	type List_Record is record
		Size	: Natural := 0;
		Head	: List_Element := null;
		Tail	: List_Element := null;
	end record;

	type List is access List_Record;


package body List is
	procedure List_Destroy(Lst	: in out List)
		Tmp	: Item;
	begin
		.
		.
		while Lst.Size /= 0 loop
			.
			.
			if Item_Destroy /= null then
				Item_Destroy(Tmp);
			end if;
			.
			.
		end loop
		Free(Lst);
	end List_Destroy;
	.
	.

Of course this code is Invalid
But I want to make default generic formal parameter(?)...
How I can do it?

I am not a native speaker of English. I am sorry...

Re: default generic parameter ?

[Marius Amado Alves]

On 17 Mar 2005, at 02:43, Bini wrote:

> generic
> 	type Item is private;
> 	with procedure Item_Destroy(I : out Item) := null; -- Invalid 
> syntax...

There is this construct:

   generic
      with procedure Op is <>;

but then on instantiation a matching procedure must exist. I think to 
do what you want you must write:

   type Op_Ptr is access procedure;
   generic
     Op : Op_Ptr := null;

Re: default generic parameter ?

[Bini]

Thank you for your response... ^^