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Groups > comp.lang.c++ > #80638

Re: dynamic_cast

From Bonita Montero <Bonita.Montero@gmail.com>
Newsgroups comp.lang.c++
Subject Re: dynamic_cast
Date 2021-07-03 15:53 +0200
Organization A noiseless patient Spider
Message-ID <sbpq4k$ql6$1@dont-email.me> (permalink)
References <20210627225136.00005d66@reddwarf.jmc> <sbbr3u$a3j$1@dont-email.me> <sbl7mh$kb5$1@dont-email.me> <sbpm58$tfv$1@dont-email.me> <oMZDI.15364$SA.31@fx39.iad>

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>> Using dynamic_cast instead of a virtual function call is bad coding.

> Incorrect, often to add the virtual function call to get around the need
> for the dynamic_cast requires injecting into a class concepts that it
> should not be dealing with.

If you're doing a dynamic_cast you're switching upon the type of the
class. This switching should be better done inside the class with class
-dependent code - with a virtual function call.

> As an example, say you have a collection of animals, and you want to
> extract all the dogs out of it. You could add to Animal and Dog an isDog
> function, (and then need to change Animal again for each new type of
> thing you might want get, lousy encapsulation) or you can use a
> dynamic_cast to check if this animal is a Dog.

the isDog-function would be faster.

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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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