How to create `NULL`?

[chfritz]

I've found in various situations the need to pass NULL as a parameter but wasn't able to create it, e.g., to call https://gstreamer.freedesktop.org/documentation/webrtc/index.html?gi-language=javascript#webrtcbin::get-stats with a NULL pad. I've tried null but get:

TypeError: Cannot convert value "null" to type GstPad

If I try new Gst.Pad(null) instead I get:

** (node:10962): CRITICAL **: 12:35:13.471: gst_webrtc_bin_get_stats: assertion 'pad == NULL || GST_IS_WEBRTC_BIN_PAD (pad)' failed

So for some reason null in JS is not translated to NULL in C.

What's the correct way to set a parameter when the C documentation of the gtk method requires NULL?

Minimal example:

const gi = require('node-gtk');
const Gst = gi.require('Gst', '1.0');
const GObject = gi.require('GObject');
const GstWebRTC = gi.require('GstWebRTC');

gi.startLoop();
Gst.init();

const p = Gst.parseLaunch('fakesrc ! webrtcbin name=webrtc');
const w = p.getByName('webrtc');
w.emit('get-stats', null, Gst.Promise.newWithChangeFunc((promise) => 
  console.log('got stats', promise)));
// Uncaught TypeError: Cannot convert value "null" to type GstPad

(Move here from #11 (comment).)

[romgrk]

I've been trying to find the typing annotations for that function but couldn't find them, Gst is a particular module.

I'm not sure if the annotations are wrong or if we should be allowing null in general for pointer types, but if it's the later then we'll need to update the conversion functions to accept null pointers:

• node-gtk/src/value.cc

  Line 1370 in 4ade970

  bool CanConvertV8ToGValue(GValue *gvalue, Local<Value> value) {

• node-gtk/src/value.cc

  Line 1421 in 4ade970

  bool V8ToGValue(GValue *gvalue, Local<Value> value, bool mustCopy) {

• node-gtk/src/boxed.cc

  Line 441 in 4ade970

  void* PointerFromWrapper(Local<Value> value) {

But I don't have enough time to implement the changes myself these days. PR welcome.