On Thu, Jan 20, 2005 at 02:11:35PM +0100, Stefan Slapeta wrote:
Jonathan Wakely wrote:
No. Unless the member is instantiated it will not be initialised. Since whether it is instantiated depends on whether you use it, which might depend on whether you've got testing/loggin/debugging code turned on, to guarantee that the member is initialised even when not used you might have to explicitly instantiate it for each specilalisation:
template const int static_<int>::member = 0; template const bool static_<bool>::member = true;
If you ever access the member by calling static_<A>::get() in some piece of _instantiated code_ it's guaranteed that static_<A>::member is going to be instantiated (at program startup).
Yeah. I guess I was talking more about the general case, not your specific static_ class. For a more complicated class you could instantiate the class but that static member will not get instantiated unless used. For static_ it's pretty hard to instantiate it and not cause instantiation of the member too :-) For more complex code, where member might only get used in a debug build, you can't rely on it being instantiated in other builds.
Of course, this is not the case for e.g. function templates that are never instantiated or for inline functions that are not actually called. However, I think it's rather a feature than a bug not to instantiate a static_<A> member if the code is never executed.
Yes, I agree. I was just pointing out that behaviour and that you can't rely on static members of templates always being instantiated. If I've just confused the issue I apologise, for anyone unclear what I mean the attached file shows that although A<int> and A<char> are both instantiated, only A<int>::member is instantiated. jon