Re: The old "Object.Method" syntax debate

[Preben Randhol <randhol+abuse@pvv.org>]

David C. Hoos wrote:
> 
> "Preben Randhol" <randhol+abuse@pvv.org> wrote in message
>> But how is it done?
>>
>> I mean how can the compiler know that a procedure say:
>>
>>    procedure Marry (Person : Man; Person2 : Woman);
>>
>> should be able to call like this:
>>
>>    type Him : Man;
>>    type Her : Woman;
>>
>>
>>    Him.Marry (Her);
>>    --  or
>>    Her.Marry (Him);
>>
>> If I have understood the change suggested.
>>
>> Would it not make the language ambigous?
> 
> It would not make the language ambiguous.  Since Him and Her
> are objects of different types, each type would need its own
> version of the Marry procedure, unless they were both derived
> from a common ancestor type which had a class-wide Marry
> procedure.

This means that this method will depend upon which type is defined as
the first argument. So then one need to do:

   procedure Marry (Person : in out Man; Muse : in out Woman)
   is
   begin
      --  Exchange rings and all
   end;

   procedure Marry (Muse : in out Woman; Person : in out Man);
   is
   begin
      Person.Marry (Muse);
   end;

This isn't more verbose than:

   Relations.Marry (Joe, Jane);

Besides now there is a subtle "the type owning the procedure must be listed
first" rule.

   Can one then still do something like:

   procedure Marry (Person : in out Man; Muse : in out Woman; Place : in Location)

   Joe.Marry (Place => Church, Muse => Jane);
-- 
Preben Randhol                    http://www.pvv.org/~randhol/