On Wed, 29 Jul 2009 19:46:20 -0300 Gustavo Sverzut Barbieri <barbi...@profusion.mobi> said:
overall i like the idea. it's a more structured way to have arbitrary smart callback signal names. it's runtime discoverable. while we're at it... it means the strings are in an array/table. they should be stringshared. imho this means that the class either should declare them with eina_stringshare - or a function that takes and array of strings will stringshare each into an internal array. then we can use if (x == y) instead of if (!strcmp(x, y)) (in fact i just changed in svn evas_object_smart_callback_call() to create a temporary stringshare of the event string to turn the compare into a ==) as for format string of the event_info. i see no reason why not. sometimes it's opaque though. ie an object handle. need a way to be able to specify that too. > Hello all, > > I'm planning to bootstrap the guarana + elementary merge* soon** but I > want to solve an unsolved problem first: help bindings and users of > evas_object_smart_callback*. > > If you're out of time to read it in detail, skip to end and read > "Summary" at least. > > = Problem = > Evas smart objects can emit signals with data, but these are > free-form. Nobody knows which signals are emitted or which type of > data they carry. This makes life of users harder since they have to > grep for code or hope that there is documentation and it's up to date, > which is quite hard we know. For bindings it's even worse, as we have > to do it and write specific mappers for each signal, that's very > boring and error prone. > > = Solution = > I would like to avoid breaking current code, so changing things > drastically is a no go. I could also propose a new system with signal > inheritance and index access to speed up dispatching and all, but I > guess the best is to build on top of existing stuff as it's "fine" for > our use cases. > > The proposal is to add an array/list of signals-types to > Evas_Smart_Class. This array would be defined when class is created > and should not be changed afterwards. Types would be DBus-like type > strings > (http://dbus.freedesktop.org/doc/dbus-specification.html#message-protocol-signatures), > for example "iis" is accessed as a struct with two leading integers32 > followed by a string. > > USERS: We could write a script to extract such information from C > files and generate documentation. > > BINDINGS: On signal callback we just query Evas_Smart_Class from > Evas_Object then type from it. With type we can query a hash that > dispatch function for that type, converting native types to wrapped > types. > > I don't plan to enforce checking on evas_object_smart_callback_call(), > but that could be a compile/run time toggle to help spotting bugs. > > = Problems = > - inheriting from another class would not automatically copy signals. > This could be worked around with a new call > "evas_smart_class_inherit_from()" that would copy all members and > duplicate this array/list. > > - "generic" smart objects would not be able to cooperate with it. I > clearly don't care much about this case as I find it abuse and not the > best solution as it would make bindings nearly impossible to do > efficiently. Unfortunately this is a real world case and raster likes > it, current elementary is built just like that, with a single > "elm_widget" class and all other widgets set hooks instead of > inheriting. A possibly solution for it is to add extra pointer per > Evas_Object_Smart with per-object signals. Then one could register > signals per instance as well as per class. I dislike it though. > > > > = Summary = > EVAS_SMART_CLASS_VERSION -> 4 (version++) > struct Evas_Smart_Class: add > const struct Evas_Smart_Callback { const char *name, const char > *type; } *callbacks; > > // pseudo code: > const char *evas_object_smart_callback_type_get(Evas_Object *o, const > char *callback_name) > { > const struct Evas_Smart_Callback *cb; > > cb = _evas_object_smart_callback_get(o->instance_callbacks, > callback_name); if (cb) return cb->type; > > const Evas_Smart *smart = evas_object_smart_smart_get(o); > const Evas_Smart_Class *sc = evas_smart_class_get(smart); > cb = _evas_object_smart_callback_get(sc->callbacks, callback_name); > if (cb) return cb->type; > > error("no callback %s in object %p (%s) type %s\n", callback_name, > o, o->name, smart->name); > return NULL; > } > > // pseudo code: > Eina_Bool evas_smart_class_inherit(Evas_Smart_Class *dst, const > Evas_Smart_Class *src) > { > if (!dst || !src) return 0; > memcpy(dst, src, sizeof(Evas_Smart_Class)); > dst->callbacks = _evas_smart_class_callbacks_dup(src->callbacks); > return 1; > } > > we can add variants to add extra callbacks or even provide functions > to just manipulate callbacks (join, copy) and let user handle it, > like: > my_sc->callbacks = evas_smart_callbacks_join(parent_sc->callbacks, > my_sc_extra_callbacks); > > > > = Notes = > * merge: no, it's not a miracle and I don't suddenly have time to do > it all, but I guess I can bootstrap it and have more people to do the > conversion of remaining parts. I'll probably do the 1% of the work, > but I guess it's the tricky part and rest is basically copy & paste, > sed, etc. > ** no deadlines yet, but I'll do my best. > > -- > Gustavo Sverzut Barbieri > http://profusion.mobi embedded systems > -------------------------------------- > MSN: barbi...@gmail.com > Skype: gsbarbieri > Mobile: +55 (19) 9225-2202 > > ------------------------------------------------------------------------------ > Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day > trial. Simplify your report design, integration and deployment - and focus on > what you do best, core application coding. Discover what's new with > Crystal Reports now. http://p.sf.net/sfu/bobj-july > _______________________________________________ > enlightenment-devel mailing list > enlightenment-devel@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/enlightenment-devel > -- ------------- Codito, ergo sum - "I code, therefore I am" -------------- The Rasterman (Carsten Haitzler) ras...@rasterman.com ------------------------------------------------------------------------------ Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july _______________________________________________ enlightenment-devel mailing list enlightenment-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/enlightenment-devel
