Re: Merits of re-dispatching

[dmitry@elros.cbb-automation.de (Dmitry A. Kazakov)]

On Thu, 21 Feb 2002 05:49:10 GMT, Hyman Rosen <hyrosen@mail.com>
wrote:

>Dmitry A. Kazakov wrote:
>> My interpretation was that if C++ dispatches then it treats the type
>> as class wide,, otherwise as specific. Then the  object is always
>> treated as specific in all calls from destructor. So what? Maybe it is
>> hard to simulate, but well possible to explain.
>
>I don't know what it is you think that C++ does, but in fact, all calls
>to virtual methods in C++ are dispatching, unless you ask for a specifc
>version using the pointer->CLASS::FUNCTION() notation. In constructors
>and destructors, the type of the object is the type whose constructor
>or destructor is running, and that is the type used for dispatching.

OK, it dispatches as if it didn't. Therefore I say that it does not.
What happens internally is of no interest.

>If the compiler can deduce the actual type of an object in a dispatching
>call, it is of course free to call the proper method directly, and it
>may be the case that such deduction is easier in a constructor or
>destructor, but that is completely irrelevant to understanding what is
>happening from the language viewpoint.

The viewpoint of C++ language, but I am not talking about C++
definition of "dispatch" and its implementation issues.

>You may persist in maintaining your incorrect mental model of what is
>going on, but the only effect will be to lead you astray in complicated
>caes.

I still prefer a model where types of objects are not arbitrarily
changed [no matter physically or mentally] depending on what kind of
method is used.

Regards,
Dmitry Kazakov