Install

pip install revisiondict

Example

>>> from revisiondict import RevisionDict
>>> d = RevisionDict()
>>> d.revision                    # get revision (is 0 at init)
0
>>> d.base_revision               # get revision before oldest change
0

Adding new items:

>>> d['a']=0; d['b']=1; d['c']=2  # make three updates
>>> d.revision                    # showing 3 changes
3
>>> d.base_revision               # get revision before oldest change
0

Inspecting content of RevisionDict:

>>> d.checkout()=={'a': 0, 'b': 1, 'c': 2} # get a dictionary with all changes
True
>>> d.checkout(2)                 # get all changes starting with rev. 2
{'c': 2}
>>> d.checkout(3)                 # all changes starting with actual revision
{}
>>> d.key_to_revision('b')        # revision where 'b' was changed last time
2
>>> d
RevisionDict([_Item(key='a', value=0, revision=1), _Item(key='b', value=1, revision=2), _Item(key='c', value=2, revision=3)])

Update items:

>>> d['a']=3                      # update value of 'a' (was 0 before)
>>> d.revision
4
>>> d.base_revision
1
>>> d.key_to_revision('a')
4
>>> d.checkout(3)                 # get all changes starting with rev. 3
{'a': 3}
>>> tuple(d.keys())               # iterate over keys (ordered by time of update)
('b', 'c', 'a')

UniqueRevisionDict

UniqueRevisionDict is a subclass of RevisionDict which does not create a new revision, when an element is updated with the same value.

>>> from revisiondict import UniqueRevisionDict
>>> d = UniqueRevisionDict(a=0)
>>> d.revision
1

>>> d['a']=0  # value is equal to the previous one
>>> d.revision
1

>>> d['a']=False  # value is still equal as 0 == False
>>> d.revision
1

>>> d['a']=100  # a new value is set, so revision is increased
>>> d.revision
2