matthandlersux

in python:

from pprint import pprint
from collections import defaultdict


# one-line definition of a tree:
def tree(): return defaultdict(tree)

kiy0taka

One line Tree in Groovy

The other day, I saw Harold Cooper's One-line tree in Python via autovivication, and wondered if the same thing was possible in Groovy.

The answer is yes! But you need to define the variable tree before you can assign it to the self-referential withDefault closure, hence with Groovy, it's a two-line solution ;-)

Anyway, given:

def tree = { [:].withDefault{ owner.call() } }

upsuper

一行 Python 实现树

使用 Python 内置的 defaultdict，我们可以很容易的定义一个树形数据结构：

def tree(): return defaultdict(tree)

就是这样！