Hi, I'm trying to generate a gobject-introspection binding for a library, and am facing some problems I couldn't find the answer to.
First, no, the library isn't really GObjec-based. However that was not the problem, I added appropriate boxed GTypes, and the GIR mostly works [1][2]. So, my GIR works mostly as expected from Vala [3], Python and GJS. Great. However, here comes the tricky problem: my library has a custom generic value type, which supports integers, reals, strings, and arrays. So, I wanted to add wrapping API that take GValues to integrate seamlessly with the languages: ..._push_gvalue(..., GValue *value, ...); so that the higher level language using the GIR could pass natural types: ...push(..., 42); ...push(..., "hello"); ...push(..., [1, 2, "hello", [2, 3, 4]]); It works just fine with integers, reals and strings. But it doesn't do anything good with arrays. The problem is, I guess, because GI doesn't have a canonical generic array type [4], so language bindings don't know what they should do when trying to pass an array as a GValue. Python passes in a boxed PyObject (what am I supposed to do with that?), GJS basically errors out complaining it can't convert the array, and Vala doesn't compile code passing in a native array (`int[]` for example, nor even `GValue?[]`). With Vala I can make it work by explicitly giving a `Array<Value?>`, which properly gets boxed, and that I can read (of course, it's plain C after all), but I can't even find these APIs in Python or GJS. Of course, I could add separated API for arrays like this: ..._push_gvalue_array(..., GValue **values, gsize n_values, ...); It works, but of course only for a single-level array (fails the same with an array containing array members) -- and having separate API for the array case is also not very nice. I also gave GVariant a quick shot, but while it works quite well with Vala (well, similarly to GValue, with the addition it knows about arrays), it doesn't seem to have any kind of magic integration for creating variants with Python or GJS [5] -- and then becomes extremely verbose. Also, I'm not quite sure GVariant is meant to be used that way, so maybe it's abusing the API? Anyway, my question is: is there a way to pass generic arrays implicitly as GValue (e.g. a GArray of GValue*, but I'm open to anything usable from C), or is this a lost cause? And if my only way is to manually build arrays, does Python and GJS have a way of building a GArray, or some other similar GLib array type? There is no constructor for GLib.Array in GJS apparently, and I didn't find any in Python either. BTW, I similarly need to be able to return an array and this array be usable by the calling language. Returning a GArray boxed in a GValue "works", but that array is not really usable (not interface to access it in Python, and GJS tells me without surprise that it is "Unable to introspect element-type of container in GValue"). GVariant seems a little more usable there. Thanks for reading through :) Regards, Colomban Notes: [1] though, while it works with GJS and Python, apparently Seed doesn't allow boxed types of unknown size and asserts out when calling the constructor. [2] but apparently boxed type constructors can't have arguments, which is somewhat problematic -- but that's not important for me, at least not now. [3] Vala is a bit annoying because of https://bugzilla.gnome.org/show_bug.cgi?id=670167, but I get it and it can be worked around. [4] there is GValueArray, but it's now deprecated. [5] but Python seems to have some support for reading them, as they are iterable, printable, and (to some extent) usable as a value _______________________________________________ gtk-app-devel-list mailing list gtk-app-devel-list@gnome.org https://mail.gnome.org/mailman/listinfo/gtk-app-devel-list
