On Wed, Oct 21, 2009 at 3:09 PM, Ireneusz Szpilewski <irek@szpilewski.opole.pl> wrote:
Stewart, Robert wrote:
Ireneusz Szpilewski wrote:
[...] I don't care what you call it. There is no good reason to do this in C++.
[snipped examples of using containers of heterogeneous types.]
I'm well aware of uses of this approach and they are usually misguided. A common base class is not terribly helpful. One specific to a particular use case is far more useful. Using your approach encourages programming with dynamic_cast. There are times when it is needed, but its use should be limited and not encouraged generally.
I agree that defining and using a common base class for all other classes in a project is in 99% of cases a very bad idea. There is a book called "C++ Gotchas: Avoiding Common Problems in Coding and Design" and the use of such "cosmic hierarchies" is a gotcha #97 ;-)
I think of rtti_base as of yet another screwdriver in our toolbox. The more tools we have, the more various things we can do. As you wrote: "There are times when it is needed" ;-) so, why not to have it?
Ireneusz Szpilewski
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