Re: friend classes in ada95

[Ray Blaak <blaak@infomatch.com>]

Alfred Hilscher <Alfred.Hilscher@icn.siemens.de> writes:
> I would have preferred this notation too.
> 1. "class type t is ..."  and  "t'class"   would be more clear than  
> "type t is tagged ..."   and   "t'class"
> 2. I have to write   task type t is    and not    type t is concurrent
> ...

And "protected type t", not "type t is protected". 

For that matter, given a protected type, one also writes t.Foo instead of
Foo(t).

I know people here feel strongly about the normal procedural syntax for method
calls, and it certainly helps to avoid problems, especially with defining
binary operations, but having been away from Ada for a while, and using
Delphi, C++, and Java, I have found I have changed my mind.

I am realizing the saying obj.Method is a more natural way of expressing how I
*think*. 

I like Delphi's way of doing OO:

  type TObject = class (ParentClass, Interface1, Interface2, ...)
  private
    attribute : Integer;
  public
    procedure Foo(v : Integer);
  end;

and then the implementations look like:

  procedure TObject.Foo(v : Integer);
  begin
    self.attribute := v;
  end;

I consider myself to be an experienced OO programmer, and at one time was an
expert Ada programmer, and I certainly "get" Ada's way of doing OO with tagged
types, but I find the syntax now for doing simple OO stuff tedious and not as
clear to the reader as it should be.

Multiple inheritance from interfaces should be easy. Declaring virtual methods
should be easy. In Ada, the caller decides if dispatching is desired by
ensuring a method call is in terms of a class wide parameter or not. I think
it should be the class implementor that decides, since if the caller gets it
wrong, it is a silent error.

Delphi's style makes overriding and polymorphism clear in the code:

  type TObject = class(TBaseObject)
    procedure Foo; override; // required if TBaseObject.Foo is virtual
    procedure DispatchOnMe; virtual;
  end;

Ada's style is the most "correct" since we have a true building block
approach, but I just wish the syntax was a little better.

I am spouting religious opinions to be sure, I generally like Ada very much,
and its OO style is now standardized and not going to change any time soon,
but I will still complain about it now and again.

-- 
Cheers,                                        The Rhythm is around me,
                                               The Rhythm has control.
Ray Blaak                                      The Rhythm is inside me,
blaak@infomatch.com                            The Rhythm has my soul.