On Thu, 30 Apr 2009 18:02:45 -0300 Gustavo Sverzut Barbieri <barbi...@profusion.mobi> said:
> On Thu, Apr 30, 2009 at 10:11 AM, Albin Tonnerre > <albin.tonne...@gmail.com> wrote: > > Hello, > > > > While playing with Eina_Inlist, I noticed that given a pointer to an > > Eina_Inlist, one can't easily get a pointer to the structure containing it. > > The only option now is to put the Eina_Inlist first in the structure, and > > then cast this structure to an Eina_Inlist, which is far from optimal. > > I'd therefore like to propose that we add in eina_inlist.h a macro along the > > lines of > > > > #define FIND_A_SENSBILE_NAME_FOR_THIS(ptr, type) ((type *) ((Eina_Inlist *) > > #ptr - offsetof(type, __in_list))) > > > > Then, we could get a pointer to the containing structure, no matter where > > the Eina_Inlist is (note that I used __in_list as the member as we already > > have a macro '#define EINA_INLIST Eina_Inlist __in_list', but a member > > argument could be added just as well) > > > > Thoughts ? > > As we discussed on IRC, I like this. It would help avoid casts and try > to make code bit easier to get right. much uglier as now you need to drag an offset # around all the time, and now you still need to cast anyway (use a raw pointer offset and cast to ah Inlist pointer). you don't get rid of it. inheritance in c in the end requires casting. thats how c does it. dont be afraid of casting or think its ugly. it's how c becomes powerful and flexible. -- ------------- Codito, ergo sum - "I code, therefore I am" -------------- The Rasterman (Carsten Haitzler) ras...@rasterman.com ------------------------------------------------------------------------------ Register Now & Save for Velocity, the Web Performance & Operations Conference from O'Reilly Media. Velocity features a full day of expert-led, hands-on workshops and two days of sessions from industry leaders in dedicated Performance & Operations tracks. Use code vel09scf and Save an extra 15% before 5/3. http://p.sf.net/sfu/velocityconf _______________________________________________ enlightenment-devel mailing list enlightenment-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/enlightenment-devel
