Add static boolean to track whether the callbacks system has been
initialised. This makes it possible to make the `BKE_callback_remove()`
function more noisy in case of programming errors, and avoids accessing
`funcstore->alloc` when `funcstore` was potentially already freed.
Thanks @campbellbarton for pointing this out.
`BKE_callback_remove` now checks whether the callback actually is known,
before trying to remove it.
`BKE_blender_atexit()` runs after `BKE_callback_global_finalize()`. When
an at-exit callback tried to unregister its BKE callbacks, these would
already be unregistered, causing a crash of Blender when exiting,
Introduce `BKE_callback_remove()`, which undoes the effect of
`BKE_callback_add()`. It also respects `funcstore->alloc` by freeing the
removed `funcstore` when needed.
This allows for shorter-lived objects in memory to unregister their
callbacks at the end of their lifespan.
`BKE_callback_global_finalize()` has been adjusted so that the
responsibility "remove a callback" is given to one function only.
Reviewed by: campbellbarton
Differential Revision: https://developer.blender.org/D12625
The goal is to make it possible to access evaluated datablocks at a
corresponding context. For example, be able to check evaluated state
if an object used for rendering.
Allows to write scripts in a safe manner for T63548 and T60094.
Reviewers: brecht
Differential Revision: https://developer.blender.org/D5726
Preparing for the bigger changes which will be related on passing
dependency graph to various callbacks which need it.
Differential Revision: https://developer.blender.org/D5725
