Re: Two class-wide operands, but only one controlling

[porton@ex-code.com (Victor Porton)]

In article <877kf34a3t.fsf@inf.enst.fr>,
	Samuel Tardieu <sam@rfc1149.net> writes:
>>>>>> "Victor" == Victor Porton <porton@ex-code.com> writes:
> 
> Victor> In article <ubs4gvzea.fsf@wanadoo.fr>,
> Victor> 	Pascal Obry <p.obry@wanadoo.fr> writes:
>>> porton@ex-code.com (Victor Porton) writes:
>>>
>>>> I want something like a procedure with two class-wide operands,
>>>> (of two different types) but only one of these controlling.
>>>>
>>>> The solution I found is introducing new tagged record types which
>>>> would refer to these two types and passing both operands as one
>>>> operand in such the record. Other solutions?
>>>
>>> Declare the second one as a class-wide ('Class) parameter.
> 
> Victor> What?! It is clearly stated that I want _both_ of them class
> Victor> wide...
> 
> I think you are confusing actual (in the call) and formal (in the
> declaration) parameters. Pascal proposes that you use a first
> non-class-wide formal parameter and a second class-wide formal
> parameter.

Not what I need. basically I have a container and an iterator.
Both a derived (in my case I need this) from abstract container
and abstract iterator. I need procedure like:

procedure Next
  (C: Abstract_Container'Class; I: in out Abstract_Iterator'Class);
  
but this is an error as we have two controlling operands of
different types :-( I cannot make one of these non class-wide
as both a abstract.

It was simple in C++. Ada has disadvantages...

> The actual parameter of a class-wide formal parameter cannot be a
> controlling operand.

Samuel, di you meant vice versa?