library loading api.

this is not well suited to RNA so this is a native python api.

This uses:
  bpy.data.libraries.load(filepath, link=False, relative=False)

however the return value needs to use pythons context manager, this means the library loading is confined to a block of code and python cant leave a half loaded library state.


eg, load a single scene we know the name of:
  with bpy.data.libraries.load(filepath) as (data_from, data_to):
      data_to.scenes = ["Scene"]


eg, load all scenes:
  with bpy.data.libraries.load(filepath) as (data_from, data_to):
      data_to.scenes = data_from.scenes


eg, load all objects starting with 'A'
  with bpy.data.libraries.load(filepath) as (data_from, data_to):
      data_to.objects = [name for name in data_from.objects if name.startswith("A")]

As you can see gives 2 objects like 'bpy.data', but containing lists of strings which can be moved from one into another.

release/scripts/modules/bpy_types.py

@@ -26,6 +26,7 @@ StructRNA = bpy_types.Struct.__bases__[0]
 StructMetaPropGroup = _bpy.StructMetaPropGroup
 # StructRNA = bpy_types.Struct
 
+bpy_types.BlendDataLibraries.load = _bpy._library_load
 
 class Context(StructRNA):
     __slots__ = ()