On Thu, May 4, 2017 at 7:39 PM, Nathan Froyd <nfr...@mozilla.com> wrote: > On Thu, May 4, 2017 at 12:32 PM, Henri Sivonen <hsivo...@hsivonen.fi> wrote: >> On Thu, May 4, 2017 at 4:27 PM, Nathan Froyd <nfr...@mozilla.com> wrote: >>> On Thu, May 4, 2017 at 3:08 AM, Henri Sivonen <hsivo...@hsivonen.fi> wrote: >>>> Is it feasible (with reasonably low effort) to introduce a new XPIDL >>>> type that is a pointer to a non-refcounted immutable static object in >>>> C++ and still gets bridged to JS? >>> >>> You can certainly have static objects with what amount to dummy >>> AddRef/Release methods passed through XPIDL (we do this in a couple of >>> places throughout Gecko), but I don't think you can get away with >>> having a non-refcounted object passed through XPIDL. >> >> Do the AddRef/Release need to be virtual? > > Yes. (I'm not sure how XPConnect would discover the refcounting > methods if they were non-virtual.) > > Please note that the static objects with dummy AddRef/Release methods > also implement XPConnect interfaces, i.e. QueryInterface, nsresult > virtual methods, etc.
OK. That doesn't fit my case. There's nothing virtual on either the C++ or Rust side about mozilla::Encoding / encoding_rs::Encoding. All the instances come from the Rust side and the interpretation of the pointer just changes when crossing the FFI so that C++ thinks it's a pointer to mozilla::Encoding. On the C++ side, the (all non-virtual) methods take the "this" pointer and send it back to Rust as the first argument to FFI. > I think you could possibly make your things a WebIDL interface, which > don't require refcounting, and magically make the WebIDL interfaces > work with XPIDL, but I do not know the details there. I'll keep that in mind. Thanks. Another option is to have dual methods on objects that are accessed from both C++ and JS: A non-scriptable method that takes const mozilla::Encoding* and a scriptable method that takes something else: either a string containing a name or some kind of manually-applied XPCOM/XPIDL-ish wrapper for const mozilla::Encoding*. It just would be nice for the wrapping part to be automagic in the binding. -- Henri Sivonen hsivo...@hsivonen.fi https://hsivonen.fi/ _______________________________________________ dev-platform mailing list dev-platform@lists.mozilla.org https://lists.mozilla.org/listinfo/dev-platform
