Module Registry

Registry

This module provides a way to create, retrieve and edit persistent data in Blender. When a script runs in Blender, it has its own private global dictionary, which is deleted when the script finishes. This is done to avoid problems with name clashes and garbage collecting. But the result is that data created by a script isn't kept after it leaves, for itself or others to access later: the data isn't persistent. The Registry module was created to give script authors a way around this limitation.

In Python terms, the Registry holds a dictionary of dictionaries. You should use it to save Python objects only, not BPython (Blender Python) objects -- but you can save BPython object names, since those are strings. Also, if you need to save a considerable amount of data, please save to a file instead. There's no need to keep huge blocks of memory around when they can simply be read from a file.

Two uses for this module:

a) To save data from a script that another script will need to access later.

b) To save configuration data from your script's gui (button values) so that the next time the user runs your script, the changes will still be there. Later we can make Blender save the Registry so that its data won't be lost after users quit the program. And also add an option to save as a Text that can be kept in a .blend file, letting users keep script data there.

 import Blender
 from Blender import Registry

 # first declare your global variables:
 myvar1 = 0
 myvar2 = 3.2
 mystr = "hello"

 # then check if they are already at the Registry (saved on a
 # previous execution of this script):
 dict = Registry.GetKey('MyScript')
 if dict: # if found, get the values saved there
   myvar1 = dict['myvar1']
   myvar2 = dict['myvar2']
   mystr = dict['mystr']

 # let's create a function to update the Registry when we need to:
 def update_Registry():
   d = {}
   d['myvar1'] = myvar1
   d['myvar2'] = myvar2
   d['mystr'] = mystr
   Blender.Registry.SetKey('MyScript', d)

 # ...
 # here goes the main part of the script ...
 # ...

 # at the end, before exiting, we use our helper function:
 update_Registry()
 # note1: better not update the Registry when the user cancels the script
 # note2: most scripts shouldn't need to register more than one key.