Re: Ada 2005?

[jayessay <nospam@foo.com>]

"Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> writes:

> On 20 Dec 2004 18:44:14 -0500, jayessay wrote:
> 
> > "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> writes:
> > 
> >> Copy is a friend, but they are not methods. C++ does not support multiple
> >> dispatch.
> > 
> > Yes, but to be clear, neither does Ada.
> 
> Surprisingly, but it does:
> 
> procedure Foo (X, Y : Some_Tagged_Type); -- This is legal
> 
> Though it is very limited and cannot be counted as true multiple dispatch.


Right.  All the parameters in a dispatching call to such a case must
resolve to the _same_ type (IIRC) and so it isn't "multiple" dispatch
at all.  True multiple dispatch occurs when such profiles can be
called where the parameters resolve to different types (often not even
in the same branch of the type hierarchy) and the correct method is
dynamically invoked (1,2).


/Jon

1. For an example of of multiple dispatch, see generic functions,
   method resolution and dispatch in CLOS:

http://www.lispworks.com/reference/HyperSpec/Body/07_f.htm
http://www.lispworks.com/reference/HyperSpec/Body/07_ff.htm


2. Overloading gives a kind of static version of this.

-- 
'j' - a n t h o n y at romeo/charley/november com