Re: dynamic_cast

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From	Mr Flibble <flibble@reddwarf.jmc>
Newsgroups	comp.lang.c++
Subject	Re: dynamic_cast
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On Sat, 3 Jul 2021 13:59:14 -0400
Richard Damon <Richard@Damon-Family.org> wrote:

> On 7/3/21 12:04 PM, Bonita Montero wrote:
> >> Wrong, the NUMBER of functions needed grows way to fast to be
> >> scalable.  
> > 
> > Use an enum and return an enum-value in _one_ function.
> > That's faster than a dynamical downcast.  
> 
> Doesn't handle the Animal -> Mammel -> Canine -> Dog -> Poodle case
> without a big lookup table to say that Poodles are also Dogs and
> Canines, and Mammels.
> 
> You STILL need to edit the Animal.h file every time you add new
> derived class. Lack of Encapsulation.

You are both wrong; if you are using dynamic_casts or isDog() then that
suggests you animal abstraction isn't elaborate enough, animal class
should include a list of behaviours as child objects (i.e. composition
instead of inheritance) and one such behaviour might be barking,
canBark(), and could be used together with the visitor pattern, for
example.

/Flibble

Thread

dynamic_cast Mr Flibble <flibble@reddwarf.jmc> - 2021-06-27 22:51 +0100
  Re: dynamic_cast Öö Tiib <ootiib@hot.ee> - 2021-06-27 15:01 -0700
  Re: dynamic_cast Branimir Maksimovic <branimir.maksimovic@gmail.com> - 2021-06-27 22:30 +0000
  Re: dynamic_cast "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2021-06-27 16:35 -0700
  Re: dynamic_cast Bonita Montero <Bonita.Montero@gmail.com> - 2021-06-28 08:44 +0200
    Re: dynamic_cast Vir Campestris <vir.campestris@invalid.invalid> - 2021-07-01 21:14 +0100
      Re: dynamic_cast Öö Tiib <ootiib@hot.ee> - 2021-07-01 14:16 -0700
      Re: dynamic_cast red floyd <no.spam.here@its.invalid> - 2021-07-01 17:48 -0700
      Re: dynamic_cast Bonita Montero <Bonita.Montero@gmail.com> - 2021-07-03 14:45 +0200
        Re: dynamic_cast Richard Damon <Richard@Damon-Family.org> - 2021-07-03 09:39 -0400
          Re: dynamic_cast Bonita Montero <Bonita.Montero@gmail.com> - 2021-07-03 15:53 +0200
            Re: dynamic_cast Richard Damon <Richard@Damon-Family.org> - 2021-07-03 09:59 -0400
              Re: dynamic_cast Bonita Montero <Bonita.Montero@gmail.com> - 2021-07-03 17:01 +0200
                Re: dynamic_cast Richard Damon <Richard@Damon-Family.org> - 2021-07-03 11:42 -0400
                Re: dynamic_cast Bonita Montero <Bonita.Montero@gmail.com> - 2021-07-03 18:04 +0200
                Re: dynamic_cast Richard Damon <Richard@Damon-Family.org> - 2021-07-03 13:59 -0400
                Re: dynamic_cast Mr Flibble <flibble@reddwarf.jmc> - 2021-07-03 20:06 +0100
                Re: dynamic_cast Bonita Montero <Bonita.Montero@gmail.com> - 2021-07-04 07:06 +0200
                Re: dynamic_cast Richard Damon <Richard@Damon-Family.org> - 2021-07-03 14:03 -0400
                Re: dynamic_cast Tim Rentsch <tr.17687@z991.linuxsc.com> - 2021-08-07 13:06 -0700

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