>>> from dot import Dot
>>> class This(Dot):
...     def __init__(self, *args, **kwargs):
...         super(This, self).__init__(*args, **kwargs)
...         self.items = {}
...     def load(self, paths):
...         return {i: self.items[i] if i in self.items else "value %s" % i for i in paths}
...     def save(self, path, value):
...         self.items[path] = value
... 

>>> this = This()
>>> aa = this.part1.part2.part3.part4
>>> aa
<Lazy object: this.part1.part2.part3.part4>
>>> print(aa)
value this.part1.part2.part3.part4
>>> aa
value this.part1.part2.part3.part4

>>> this = This()
>>> aa = this.part1
>>> aa
<Lazy object: this.part1>
>>> bb = this.part2
>>> bb
<Lazy object: this.part2>
>>> print(aa)
value this.part1
>>> aa
value this.part1
>>> bb
value this.part2

>>> bb = this.part1.part2.i120
>>> bb
<Lazy object: this.part1.part2.120>
>>> print bb
value this.part1.part2.120

>>> cc = this['part1.part2.part4']
>>> cc
<Lazy object: this.part1.part2.part4>
>>> dd = this['part1.%s.part4' % 100]
>>> dd
<Lazy object: this.part1.100.part4>
>>> path = 'part1.part2'
>>> this[path] = 'This was set by a dynamic key.'
>>> this.path
This was set by a dynamic key.

>>> this.part1.part2.part3.part4 = "new value"
>>> zz = this.part1.part2.part3.part4
>>> zz
new value

>>> class That(This):
...    pass
>>> that = That()
>>> aa = that.something
>>> print(aa)
value that.something
>>> bb = this.something
>>> bb
<Lazy object: this.something>

>>> aa = this.part1
>>> print aa
value this.part1
>>> bb = this.part1 # reads from the cache
>>> this.flush()
>>> bb = this.part1 # Will evaluate this.part1 again