Re: Calling through function pointer--syntax question

[Philip Anderson <phil.anderson@amsjv.com>]

Simon Wright wrote:
> 
> This has to be the second P. If you were meaning to call the first P,
> you would write

Would or must?
 
>     P (func.all (5));
> 
>   with Ada.Text_Io; use Ada.Text_Io;
>   Procedure Q is
>     type Func_Ptr is access function (Param : Integer) return Integer;
>     function Actual (Param : Integer) return Integer is
>     begin
>       return 0;
>     end Actual;
>     function Func (Y : Integer := 4) return Func_Ptr is
>     begin
>       return Actual'Access;
>     end Func;
>     procedure P (X : in Integer) is
>     begin
>       Put_Line ("first interpretation");
>     end P;
>     procedure P (X : in Func_Ptr) is
>    begin
>       Put_Line ("second interpretation");
>     end P;
>   begin
>     P (Func (5));
>     P (Func.all (5));
>   end Q;
> 
> results in
> 
>   second interpretation
>   first interpretation
> 
> (GNAT 3.14a)

Using Rational Apex for NT 3.0.2b, this gives an error:

*** Unit has semantic errors
P could be (in Q) P
P could be (in Q) P
P (Func (5)); is an ambiguous call

Commenting out the second P, it compiles quite happily, resulting in

first interpretation
first interpretation


Likewise, using named parameter association to disambiguate calls

P (Func (Param => 5));
P (Func (Y => 5));
P (Func.all (5));

which is accepted, and results in

first interpretation
second interpretation
first interpretation


So I think Adam does have a case.  Also, either Rational or Gnat appears
to have a bug.


-- 
hwyl/cheers,
Philip Anderson
Alenia Marconi Systems
Cwmbr�n, Cymru/Wales