[Devel] What is a feature? (extension_data)

Stefano D'Angelo zanga.mail at gmail.com
Sat Oct 29 06:19:21 PDT 2011

2011/10/28 David Robillard <d at drobilla.net>:
> The current release of LV2 has some confusing comments about
> extension_data.  It's not really clear just what a "feature" is, and how
> the plugin data would indicate that the plugin provides some
> extension_data (despite the comment saying that they must).

Do we actually need that the plugin data says anything about
extension_data being not NULL/doing anything useful? Anyway, I can't
find the comment you are referring to...

However, I have checked the current extensions on lv2plug.in and the
only ones making use of extension_data() are persist, data-access and
ui-resize that uses the equivalent extension_data() for UIs. Now, in
all of these cases I don't think it's really possible to determine
whether a feature is a host feature or a plugin feature, to me it
looks it's always somehow a combination of the two, and also I see no
need to make such distinctions.


P.S.: for the record, I think there is at the very least some overlap
with the LV2_Feature array in instantiate(), I guess we could just
have avoided having extension_data() in the first place.

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