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This is often invalid, outdated or misleading
especially when splitting files.
It's more useful to git-blame to find out who has developed the code.
See P901 for script to perform these edits.
See https://developer.blender.org/D2417 for details.
Note that since static overrides rely heavily on RNA, this commit is
essentially invisible from user PoV, more in next commits.
Fix is a bit ugly, but cannot think of another solution for now, at
least this **should** not break anything else.
And now I go find myself a very remote, high and lonely mountain, climb
to its top, roar "I hate proxies!" a few times, and relax hearing the echos...
Was a waaaaayyyyy to much generic name for such a specific func, renamed
to much more descriptive BKE_libblock_relink_to_newid().
In near future (few weeks, to limit as much as possible silent mismatch
in branches), will rename BKE_libblock_relink_ex to BKE_libblock_relink,
this is the real generic data-block relinking func!
Those 'never null' ID pointers are really a PITA to handle... luckily we don't have much of those around!
Found by Sybren, thanks.
Should be backported to 2.78.
Main issue was that BKE_libblock_relink_ex was pretty much ignoring all those...
Also, unlinking of objects was not handling correctly indirect-related flags.
Refactored code into helper functions to avoid too much duplicated code.
This is in fact very hairy situation here... Objects are only refcounted by scenes,
any other usage is 'free', which means once all object instanciations are gone Blender
considers it can delete it.
There is a trap here though: indirect usages. Typically, we should never modify linked data
(because it is essencially useless, changes would be ignored and ost on next reload or
even undo/redo). This means indirect usages are not affected by default 'safe' remapping/unlinking.
For unlinking preceeding deletion however, this is not acceptable - we are likely to end with
a zero-user ID (aka deletable one) which is still actually used by other linked data.
Solution choosen here is double:
I) From 'user-space' (i.e. outliner, operators...), we check for cases where deleting datablocks
should not be allowed (indirect data or indirectly used data), and abort (with report) if needed.
II) From 'lower' level (BKE_library_remap and RNA), we also unlink from linked data,
which makes actual deletion possible and safe.
Note that with previous behavior (2.77 one), linked object would be deleted, including from linked data -
but then, once file is saved and reloaded, indirect usage would link back the deleted object,
without any instanciation in scene, which made it somehow virtual and unreachable...
With new behavior, this is no more possible, but on the other hand it means that in situations of dependency cycles
(two linked objects using each other), linked objects become impossible to delete (from user space).
Not sure what's best here, behavior with those corner cases of library linking is very poorly defined... :(
Also define single callback func typedef, cleaner this way!
Note: maybe we want to do that for the other callbacks too (data, etc.), but will be enough for now.
This commit changes a lot of how IDs are handled internally, especially the unlinking/freeing
processes. So far, this was very fuzy, to summarize cleanly deleting or replacing a datablock
was pretty much impossible, except for a few special cases.
Also, unlinking was handled by each datatype, in a rather messy and prone-to-errors way (quite
a few ID usages were missed or wrongly handled that way).
One of the main goal of id-remap branch was to cleanup this, and fatorize ID links handling
by using library_query utils to allow generic handling of those, which is now the case
(now, generic ID links handling is only "knwon" from readfile.c and library_query.c).
This commit also adds backends to allow live replacement and deletion of datablocks in Blender
(so-called 'remapping' process, where we replace all usages of a given ID pointer by a new one,
or NULL one in case of unlinking).
This will allow nice new features, like ability to easily reload or relocate libraries, real immediate
deletion of datablocks in blender, replacement of one datablock by another, etc.
Some of those are for next commits.
A word of warning: this commit is highly risky, because it affects potentially a lot in Blender core.
Though it was tested rather deeply, being totally impossible to check all possible ID usage cases,
it's likely there are some remaining issues and bugs in new code... Please report them! ;)
Review task: D2027 (https://developer.blender.org/D2027).
Reviewed by campbellbarton, thanks a bunch.
