On 12/15/2011 8:21 AM, Victor Bazarov wrote:
On 12/15/2011 8:10 AM, john wrote:
On 12/14/2011 11:19 AM, Victor Bazarov wrote:
On 12/14/2011 10:17 AM, john wrote:
snipped ....
IME 'const_cast' is good only for one thing: to add const where one
needs an overload resolution to go a particular way. Any other use of
'const_cast' is an instance of abuse. That's just IME, of course.
Could you give an example of the use of const_cast in this case? I do
not quite follow what you are saying.
This is from memory, I don't have a good working example right now...
When you want to call a const member function for a non-const object,
and a non-const member function also exists and overloads the const one,
the non-const would be picked - it's a better match. That's where you
could force the compiler into picking the one you want:
#include <iostream>
#include <ostream>
struct foo {
void bar() const { std::cout << "const bar\n"; }
void bar() { std::cout << "regular bar\n"; }
};
int main() {
// ...
foo f;
f.bar(); // non const is picked.
const_cast<const foo&>(f).bar(); // const version
}
..something like that, anyway. It also happens in the context of a
non-const member that is [partially] implemented in terms of a const
member function, for instance. This is artificial, of course:
struct foo {
void bar() const {
std::cout << "const bar\n"; }
void bar() {
std::cout << "non-";
const_cast<const foo*>(this)->bar(); }
};
HTH
[..]
V
I see. That makes sense.
One of the issues that spurred this question (related to my func1 in the
original post) is the following. I have a 3D mesh composed of
Volumes/Faces/Edges/Vertices. So, I have a Volume, Face, Edge, and
Vertex class, each derived from a base Topology class. The mesh is
consistent, so given a particular instance of one of the classes, there
are functions that return geometry information such as connectivity. In
particular, each class has a virtual function (declared as pure virtual
at the base Topology class)
virtual void GetVolumes(std::set<Volume*> volumes);
That doesn't look right. Did you lose the ampersand before the argument
express. If you find it difficult to type, use a typedef *or* introduce