Port property Song::loop_enabled to C++

[swesterfeld]

Please merge. I ported and tested this property port.

Remarks: I tried and failed to use something like (doesn't compile).

bool loop_enabled = Bool (... STORAGE SKIP_DEFAULT SKIP_UNDO ...)

Everything works as it is, but this would catch typos. In any case, it is not a big problem.

[tim-janik]

Hi Stefan, looks interesting.

I think I would have kept using iview->container plus a few more casts instead of introducing BstTrackView.song, to ensure that iview->container and BstTrackView.song cannot get out of sync.
Your approach might be more convenient and I guess the bst_item_view_set_container() internals ensure that the two members are always set/reset in sync...

There's one other bit missing though. WIth the old proxy interface, signal connections always come in (connect+disconnect) pairs, I'll quote the relevant code lines:

Before your PR:
bse_proxy_disconnect (song.proxy_id(),
"any_signal", track_view_repeat_changed, self,
NULL);
[...]
bse_proxy_connect (song.proxy_id(),
"swapped_signal::property-notify::loop-enabled", track_view_repeat_changed, self,
NULL);

After your PR:
bse_proxy_disconnect (self->song.proxy_id(),
"any_signal", track_view_repeat_changed, self,
NULL);
self->song = NULL; /* disconnect */
[...]
self->song.on ("notify:loop_enabled", self { track_view_repeat_changed (self); });
bse_proxy_connect (self->song.proxy_id(),
NULL);

I.e. you have replaced proxy_connect() with on(), added an event handler disconnect via =NULL but forgot to remove the proxy_disconnect line for track_view_repeat_changed that belongs to the proxy_connect() you removed.

Also please reword "/* disconnect */" to be more explicit: "// disconnects event handlers"

[swesterfeld]

There's one other bit missing though. WIth the old proxy interface, signal connections always come in (connect+disconnect) pairs

I.e. you have replaced proxy_connect() with on(), added an event handler disconnect via =NULL but forgot to remove the proxy_disconnect line for track_view_repeat_changed that belongs to the proxy_connect() you removed.

Fixed.

Also please reword "/* disconnect */" to be more explicit: "// disconnects event handlers"

Fixed.

Not sure if you wanted the fixes in an extra commit (I did this) or squashed into the previous commit and delivered as non-linear push.