Quote:Original post by Shannon Barber If you have any virtual methods (pure or not) the dtor should also be virtual (this will be automatic in C++0x)
Quoted for agreement.
There are no virtual constructors, and you should always make your base class destructors virtual. If you don't, the base class slice of your object will not be destroyed, if the derived class destructor is called.
Ok, so now, I need to make the base destructor virtual? Can it still have code in it, if it's virtual?
@Mumpo and Shannon: This 2D library I am rewriting requires some very specific window constraints, such as it can't be resizable, it can be fullscreen, it can have a caption, and it can have a variable depth. Also, They don't need to allocate any memory to the depth buffer as well. The window and OpenGL environment variables are so specific that the user shouldn't have to see it.
Right now, I am only coding an SDL context and image factory, but in the future, I will be creating a pure Win32 one, and others will be able to make contexts for the Apple Mac platform as well, or if somebody is posessed enough, AllegroGL or GLFW.
Why not just pure SDL and be done with it? I don't use LGPL, I use Zlib. This is not a derivitive work, but is compatable instead. If I have multiple interfaces, or atleast the option for multiple interfaces, I don't have to worry about clashing licenses.
Quote:Original post by Verg [...] and you should always make your base class destructors virtual. If you don't, the base class slice of your object will not be destroyed, if the derived class destructor is called.
Nitpick: It's actually the other way around. The derived destructor won't get called if the base destructor is called.
If you can guarantee that no one will ever delete a base pointer to a derived instance (ofcourse you almost never can [wink]) the virtual destructor is not needed.
___________________________Buggrit, millennium hand and shrimp!
Quote:Original post by Verg [...] and you should always make your base class destructors virtual. If you don't, the base class slice of your object will not be destroyed, if the derived class destructor is called.
Nitpick: It's actually the other way around. The derived destructor won't get called if the base destructor is called.
If you can guarantee that no one will ever delete a base pointer to a derived instance (ofcourse you almost never can [wink]) the virtual destructor is not needed.
*nods* PNP > may be the best way to get this straight in your own mind would be looking at the ogre3d source or something - because that has supporting uml documents and code that show abstraction away from a particular rendering system (opengl, dx7, dx9 I believe).
Anything posted is personal opinion which does not in anyway reflect or represent my employer. Any code and opinion is expressed “as is” and used at your own risk – it does not constitute a legal relationship of any kind.
Another "funny" fact that is very important in this context:
Calling virtual functions in the constructor or destructor will most likely NOT do what you want. (This is also discussed in Stroustrups FAQ mentioned above by gumpy macdrunken)
___________________________Buggrit, millennium hand and shrimp!
