使用深拷贝实现递归

Question

我该如何在深拷贝函数对象中实现递归？以下是相关的代码（如果你需要更多，请告诉我）：

PS：我希望递归能够遍历一个经过筛选的引用列表。目标是下载并插入任何缺失的对象。

copy.py

from put import putter

class copier:
  def __init__(self, base):
    self.base = base
  def copyto(self, obj):
    put = putter(obj)
    for x in self.base.__dict__:
      put(x)

put.py

class putter:
  def __init__(self, parent):
    self.parent = parent
  def put(self, name, obj):
    self.parent.__dict__[name] = obj

Answer 1

查看一下 copy.deepcopy 的文档。如果你能通过 __getinitargs__()、__getstate__() 和 __setstate__() 来实现你想要的功能，那样会省去很多麻烦。否则，你就需要自己重新实现一遍，代码大概会是这样的：

def deepcopyif(obj, shouldcopyprop):
    copied = {} # Remember what has already been copied
    def impl(obj):
        if obj in copied:
            return copied[obj]
        newobj = *** Create a copy ***
        copied[obj] = newobj # IMPORTANT: remember the new object before recursing
        for name, value in obj.__dict__: # or whatever...
            if shouldcopyprop(obj.__class__, name): # or whatever
                value = impl(value) # RECURSION: this will copy the property value
            newobj.__dict__[prop] = value
        return newobj
    return impl(obj)