prefs.js importing Main complains about not finding Meta

[Amy C <mathematical coffee gmail com>]

Hi all,

In my prefs.js I'm trying to import imports.ui.Main.

However this causes the following error on selecting the extension in
gnome-shell:

    JS ERROR: !!!   Exception was: Error: Requiring Meta, version
none: Typelib file for namespace 'Meta' (any version) not found

I guess Main imports Meta which is not included in the import path for
gnome-shell-extension-prefs.

The workaround is not to import Main in prefs.js and leave that until
the settings.connect('changed::...') listener in extension.js.

However I'm only importing Main because I want to query
`Main.panel._leftBox.get_children().length` and depending on the
result I'll do a this._settings.set_int(...). I'm incorporating a
wrap-around effect: if the number increases past the
get_children().length I'll set it back to 0 instead.

If I defer this processing to the listener in extension.js, it's going
to look like this:

settings.connect('changed::my_key', function () {
    let value = settings.get_int('my_key');
    if (value >= Main.panel._leftBox.get_children().length) {
        value = 0;
        settings.set_int(value);
        return;
    }
    /* ... more stuff to do with value */
}

It just seems awkward because this will fire the 'changed::my_key'
signal twice, once with the first value and the proper adjusted value
of 0.

So, is there any way to import Main into prefs.js?

cheers