[gnome-builder] plugins: add details on plugin interface age

[Christian Hergert <chergert src gnome org>]

commit 848dc32b1cfa33f90620bbf6fd2d8f44801703d3
Author: Christian Hergert <chergert redhat com>
Date:   Wed Jan 27 07:40:04 2016 +0100

    plugins: add details on plugin interface age

 libide/ide-application-plugins.c |   18 ++++++++++++++++++
 1 files changed, 18 insertions(+), 0 deletions(-)
---
diff --git a/libide/ide-application-plugins.c b/libide/ide-application-plugins.c
index 2b283b8..5f7354b 100644
--- a/libide/ide-application-plugins.c
+++ b/libide/ide-application-plugins.c
@@ -51,6 +51,24 @@ ide_application_can_load_plugin (IdeApplication *self,
 
   /*
    * TODO: Do ABI check on external data.
+   *
+   * Right now, we don't have any way to check that the plugin is implementing
+   * the same version of the API/ABI that the application exports. There are a
+   * couple ways we could go about doing this.
+   *
+   * One approach might be to generate UUIDs for each plugin structure,
+   * and update it every time the structure changes. However, plenty of changes
+   * can be safe for existing modules. So perhaps we need something that has
+   * a revision since last break. Then plugins would specify which version
+   * and revision of an interface they require.
+   *
+   * Imagine the scenario that FooIface added the method frobnicate(). Previous
+   * extensions for FooIface are perfectly happy to keep on working, but a new
+   * addin that requires FooIface may require frobnicate()'s existance. So while
+   * the ABI hasn't broken, some plugins will require a newer revision.
+   *
+   * This is not entirely different from libtool's interface age. Presumably,
+   * Gedit's IAge is similar here, but we would need it per-structure.
    */
 
   return TRUE;