Toy example Noah’s ark shall function as a container for different types of animals. As the ark itself is not concerned about the difference between monkeys, penguins, and mosquitoes, you define a class Animal, derive the classes Monkey, Penguin, and Mosquito from it, and store each of them as an Animal in the ark. Once … Read more
The return of name is implementation defined : an implementation is not even required to return different strings for different types. What you get from g++ is a decorated name, that you can “demangle” using the c++filt command or __cxa_demangle.
Since your question is specific to GCC you should consult carefully the documentation for the version you are using. The documentation for GCC 4.5.2 says the following. Which from my reading would indicate that if you avoid dynamic_cast and typeid, you should be ok. That said, I have no personal experience with -fno-rtti. Perhaps you … Read more
There are several reasons why LLVM rolls its own RTTI system. This system is simple and powerful, and described in a section of the LLVM Programmer’s Manual. As another poster has pointed out, the Coding Standards raises two major problems with C++ RTTI: 1) the space cost and 2) the poor performance of using it. … Read more
An interface describes what one needs to know in order to interact in a given situation in code. Once you extend the interface with “your entire type hierarchy”, your interface “surface area” becomes huge, which makes reasoning about it harder. As an example, your “poke adjacent oranges” means that I, as a 3rd party, cannot … Read more
Does it matter which is faster, if they don’t do the same thing? Comparing the performance of statements with different meaning seems like a bad idea. is tells you if the object implements ClassA anywhere in its type heirarchy. GetType() tells you about the most-derived type. Not the same thing.
Regardless of compiler, you can always save on runtime if you can afford to do if (typeid(a) == typeid(b)) { B* ba = static_cast<B*>(&a); etc; } instead of B* ba = dynamic_cast<B*>(&a); if (ba) { etc; } The former involves only one comparison of std::type_info; the latter necessarily involves traversing an inheritance tree plus comparisons. … Read more