Re: using put procedure with a generic package

["ophir.geffen@gmail.com" <ophir.geffen@gmail.com>]

On May 8, 7:09 am, "Jeffrey R. Carter"
<spam.jrcarter....@spam.acm.org> wrote:
> ophir.gef...@gmail.com wrote:
>
> > * queues.ads:
> > with Ada.Text_IO;
> > generic
> >   type Item is private;
> >   with procedure Item_Put(The_Item : in Item);
>
> Item_Put has exactly one parameter.
>
> >   package Int_IO is new Ada.Text_IO.Integer_IO(Integer);
> >   package Int_Queues is new Queues(Item => Integer, Item_Put =>
> > Int_IO.Put); --- error here
>
> > The package compiles on its own, but when I try to compile Test_Queues
> > there is an error:
> > no visible subprogram matches the specification for "Item_Put"
>
> Ada.Text_IO.Integer_IO has the following procedures named Put:
>
> procedure Put(File  : in File_Type;
>                Item  : in Num;
>                Width : in Field       := Default_Width;
>                Base  : in Number_Base := Default_Base);
>
> procedure Put(Item  : in Num;
>                Width : in Field       := Default_Width;
>                Base  : in Number_Base := Default_Base);
>
> procedure Put(To   :    out String;
>                Item : in     Num;
>                Base : in     Number_Base := Default_Base);
>
> None of these has exactly one parameter. That's why Int_IO.Put doesn't match
> Item_Put.
>
> You can call the 2nd of these with only one explicit parameter:
>
> Int_IO.Put (Item => 7);
>
> but it still has 3 parameters; the other 2 get the default values as the actual
> parameters.
>
> You need to create a procedure that matches Item_Put:
>
> procedure Put (Item : in Integer) is
>     -- null;
> begin -- Put
>     Int_IO.Put (Item => Item);
> end Put;
>
> and use it to instantiate your generic package.
>
> --
> Jeff Carter
> "I unclog my nose towards you."
> Monty Python & the Holy Grail
> 11

Hi
Thanks for the quick reply

The problem is that the package needs to know how to handle most non-
limited types like Integer, String, Client, Plane, Book, Document, ...
The Put procedure in any of those might and should be different from
Put Integer.

And I don't want to force the package user to declare a special Put
procedure with only one var.
Is there a better way to write the package and/or a more correct way
to declare it when using it?