是否可以在Python中覆盖赋值('=')运算符?
为此有麻烦吗?也许类似于以下内容:(更新)
class Tree:
def __init__(self, item_or_tree):
self._setto(item_or_tree)
def __assign__(self, val):
self._setto(item_or_tree)
def __setitem__(self, which, to_what):
## I would like this to call __assign__ on the Tree object at _tree[which]
to_what._tree[which] = to_what
def __getitem__(self, which):
return self._tree[which]
def __len__(self): return len(self._tree)
def __eq__(self, other):
if isinstance(other, Tree):
if other._is_tree:
return (self._item == other._item) and (self._tree == other._tree)
else:
return self._item == other._item
else: return self._item == other
def _setto(self, item_or_tree):
if isinstance(item_or_tree, Tree):
self._set_from_Tree(item_or_tree)
elif isinstance(item_or_tree, dict):
self._set_from_dict(item_or_tree)
else:
self._set_from_other(item_or_type)
def _set_from_Tree(self, other_Tree):
self._tree = other_Tree[:]
self._item = other_Tree
self._is_tree = other_Tree._is_tree
def _set_from_dict(self, the_dict):
self._is_tree = True
self._item = None
self._tree = {}
for key, val in the_dict.items():
self._tree[key] = Tree(val)
def _set_from_other(self, other):
self._is_tree = False
self._tree = None
self._item = other
class TreeModel(Tree, QAbstractItemModel):
...
## a whole bunch of required overrides
## etc
...
我想要做的是实现一个通用的树结构,该结构尽可能(对我而言)直观地工作,并且与PyQt5的Model-View-Delegate体系结构无缝集成。
我希望能够将传入的item_or_tree设置为项目或树。所以我想重载在该项目上使用=运算符时调用的函数。
PyQt具有基于项目的体系结构,其中QAbstractItemModel被覆盖。(我猜)这应该返回/接受QModelIndex对象。这些是表树(2D数组)。
因此,我正在创建一个单一的树结构,该树结构可以包含自身,处理两个相反的索引范例,并且可以与Python和其他所有东西一起很好地使用。
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无法覆盖的实现
x = y
。有关赋值含义的详细信息,请参见关于Python名称和值的事实和神话。您可以
x.a = y
使用__setattr__
(大约)来覆盖它x.__setattr__('a', y)
。您可以覆盖
x[k] = y
有__setitem__
,它是(大约)x.__setitem__(k, y)
。但是您不能覆盖
x = y
。