Autovivify is simply fancy word for the behavior of creating a dictionary key-value automatically the moment an element is accessed. Python throws an error if the kv-pair was not already created.
Perl hashes/dictionaries are auto-vivified by default, not so for Python, which could be annoying, because you have to do additional checks thus breaking the normal flow of coding.
Here is how you make a auto vivifying Python dictionary and at the same time quick way to create a Tree structure :
from collections import defaultdict
from pprint import pprint
def Tree():
return defaultdict(Tree)
tree = Tree()
tree['mammal']['ape']['chimp'] = 'bobo'
pprint(tree,indent=2,compact=True)
-----
defaultdict(...,
{ 'mammal': defaultdict(...,
{ 'ape': defaultdict(...,
{ 'chimp': 'bobo'})})})
Even better, if you want cleaner print :
from collections import defaultdict
from pprint import pprint
def Tree(): return DD(Tree)
class DD(defaultdict):
__repr__ = dict.__repr__
tree = Tree()
tree['mammal']['ape']['chimp'] = 'bobo'
pprint(tree,indent=2,compact=True)
------
{'mammal': {'ape': {'chimp': 'bobo'}}}
