<p>我个人会这样做:</p>
<pre><code>#! /usr/bin/python3
import copy
class Room:
def __init__ (self, state = 'Initial'):
self.state = state
self.history = []
def morph (self, state):
clone = copy.deepcopy (self)
self.state = state
self.history.append (clone)
</code></pre>
<p>请记住,我不知道您的实际设置是否有一些限制深度复制的功能。在</p>
<p>这就产生了:</p>
^{pr2}$
<hr/>
<p>我想通常你不需要保存对象的整个状态,只需要保存值得跟踪的属性。你可以按照以下思路将这种行为打包成一个装饰师:</p>
<pre><code>#! /usr/bin/python3
import datetime
import copy
class Track:
def __init__ (self, *args, saveState = False):
self.attrs = args
self.saveState = saveState
def __call__ (self, cls):
cls._track = []
this = self
oGetter = cls.__getattribute__
def getter (self, attr):
if attr == 'track': return self._track
if attr == 'trackTrace': return '\n'.join ('{}: "{}" has changed to "{}"'.format (*t) for t in self._track)
return oGetter (self, attr)
cls.__getattribute__ = getter
oSetter = cls.__setattr__
def setter (self, attr, value):
if attr in this.attrs:
self._track.append ( (datetime.datetime.now (), attr, copy.deepcopy (value) if this.saveState else value) )
return oSetter (self, attr, value)
cls.__setattr__ = setter
return cls
</code></pre>
<p>现在我们可以这样使用这个装饰器:</p>
<pre><code>@Track ('holder')
class Book:
def __init__ (self, title):
self.title = title
self.holder = None
self.price = 8
class Person:
def __init__ (self, firstName, lastName):
self.firstName = firstName
self.lastName = lastName
def __str__ (self):
return '{} {}'.format (self.firstName, self.lastName)
r = Book ('The Hitchhiker\'s Guide to the Galaxy')
p = Person ('Pedro', 'Párramo')
q = Person ('María', 'Del Carmen')
r.holder = p
r.price = 12
r.holder = q
q.lastName = 'Del Carmen Orozco'
print (r.trackTrace)
</code></pre>
<p>如果用<code>@Track ('holder')</code>调用,则会产生:</p>
<pre><code>2013-10-01 14:02:43.748855: "holder" has changed to "None"
2013-10-01 14:02:43.748930: "holder" has changed to "Pedro Párramo"
2013-10-01 14:02:43.748938: "holder" has changed to "María Del Carmen Orozco"
</code></pre>
<p>如果使用<code>@Track ('holder', 'price')</code>调用,则会产生:</p>
<pre><code>2013-10-01 14:05:59.433086: "holder" has changed to "None"
2013-10-01 14:05:59.433133: "price" has changed to "8"
2013-10-01 14:05:59.433142: "holder" has changed to "Pedro Párramo"
2013-10-01 14:05:59.433147: "price" has changed to "12"
2013-10-01 14:05:59.433151: "holder" has changed to "María Del Carmen Orozco"
</code></pre>
<p>如果用<code>@Track ('holder', saveState = True)</code>调用,则会产生:</p>
<pre><code>2013-10-01 14:06:36.815674: "holder" has changed to "None"
2013-10-01 14:06:36.815710: "holder" has changed to "Pedro Párramo"
2013-10-01 14:06:36.815779: "holder" has changed to "María Del Carmen"
</code></pre>