每次调用python类时创建一个新副本
我需要一些指导，如何设置正确的这是我要做的。我有一个名为Attribute块的类，然后我将使用它来创建3或4个属性块对象。如下所示..。
class AttributeBlock():
def __init__(self, key, label, isClosed, isRequired, attributes):
self.key = key
self.label = label
self.isClosed = isClosed
self.isRequired = isRequired
self.attributes = attributes if attributes is not None else {}3个attributeBlock对象
AttributeBlock(
key="Sphere",
isRequired=True,
attributes=[
''' Other class objects '''
BoolProperty("ishidden", False, "Hidden"),
]
)
AttributeBlock(
key="Box",
isRequired=True,
attributes=[
''' Other class objects '''
BoolProperty("ishidden", True, "Hidden"),
]
)
AttributeBlock(
key="Circle",
isRequired=False,
attributes=[
''' Other class objects '''
BoolProperty("ishidden", True, "Hidden"),
]
)然后，我想要做的是能够将这些AttributeBlocks中的一个添加到一个对象中，确保当它被添加时，它是AttributeBlock的一个新实例，因此它的子属性对象是新的实例。
这是我将添加属性块的对象。
class ToyBox():
def __init__(self, name="", attributes=[]):
self.name = name
self.attributes = attributes[:]
newToyBox = ToyBox()
newToyBox.name = "Jimmy"伪码
def add_attribute_block(toybox = None, key = "" ):
if an AttributeBlock with the matching key exists:
add it to toybox.attributes
add_attribute_block( newToyBox, "Box" )
print newToyBox
>>
ToyBox
name="Jimmy"
attributes=[
AttributeBlock(
key="Box",
isRequired=True,
attributes=[
BoolProperty("ishidden", True, "Hidden"),
]
),
AttributeBlock(
key="Sphere",
isRequired=True,
attributes=[
BoolProperty("ishidden", True, "Hidden"),
]
)
]回答 4
Stack Overflow用户
发布于 2015-11-24 15:00:31
如果要自动跟踪所有创建的AttributeBlock对象，可以使用类属性：
class AttributeBlock():
objects = []
def __init__(self, key, label, isClosed, isRequired, attributes):
self.key = key
self.label = label
self.isClosed = isClosed
self.isRequired = isRequired
self.attributes = attributes if attributes is not None else {}
self.objects.append(self)一旦完成，add_attribute可能变成：
def add_attribute_block(toybox = None, key = "" ):
if toybox is not None:
for obj in AttributeBlock.objects:
if obj.key == key:
toybox.attributes.append(obj)
break您还可以为class属性使用映射而不是列表：
class AttributeBlock():
objects = {]
def __init__(self, key, label, isClosed, isRequired, attributes):
if key in self.objects:
# raise a custom exception
...
self.objects[key] = self然后，您可以简单地使用：
def add_attribute_block(toybox = None, key = "" ):
if toybox is not None:
if key in AttributeBlock.objects:
toybox.attributes.append(AttributeBlock.objects[key])如果要在ToyBox中放置列表对象的副本，则必须更改创建方法以允许不将该副本放到全局列表中。在这种情况下，守则将成为：
class AttributeBlock():
objects = {}
dummy = {}
def __init__(self, key, label, isClosed, isRequired,
attributes, glob = None):
if glob is None:
glob = self.objects
if key in glob:
raise ValueError(str(key) + " already exists")
self.key = key
self.label = label
self.isClosed = isClosed
self.isRequired = isRequired
self.attributes = attributes if attributes is not None else {}
if glob is not self.dummy:
glob[key] = self
def copy(self):
return AttributeBlock(self.key, self.label, self.isClosed,
self.isRequired, self.attributes[:],
self.dummy)使用一个不允许在任何容器中存储新创建的对象的虚拟类对象，以及一个允许将其存储在外部dict中的可选glob参数。还要注意copy方法，它精确地使用了dummy。
add_attribute_block变成：
def add_attribute_block(toybox = None, key = "", glob = None ):
if glob is None:
glob = AttributeBlock.objects
if toybox is not None:
if key in glob:
toybox.attributes.append(AttributeBlock.objects[key].copy())使用复制方法在ToyBox中存储未存储在全局容器中的原始对象的副本。
Stack Overflow用户
发布于 2015-11-24 14:36:33
如果要确保添加到ToyBox中的属性实例是副本，最简单的方法是使用标准复制模块
import copy
...
class ToyBox(object):
...
def add_attribute(self, attribute):
self.attributes.append(copy.deepcopy(attribute))Stack Overflow用户
发布于 2015-11-24 15:06:39
如果我正确理解，您希望每个ToyBox实例包含一个AttributeBlock实例列表，检查列表中还没有其他同名的对象。
class AttributeBlock():
def __init__(self, key): # demo, add the other parameters/attrs
self.key = key
def __str__(self):
return self.key # add the other parameters/attrs
class ToyBox(object):
def __init__(self):
self.attributes = []
def add_attr(self, a):
gen = (attr for attr in self.attributes if attr.key == a.key)
try:
next(gen)
except StopIteration:
self.attributes.append(a)
def __str__(self):
return ','.join(map(str,self.attributes))所以现在我们可以
>>> toy = ToyBox()
>>> toy.add_attr(AttributeBlock("Box"))
>>> toy.add_attr(AttributeBlock("Sphere"))
>>> toy.add_attr(AttributeBlock("Box"))
>>> print toy
Box,Sphere正如您注意到的，使add_attribute函数成为ToyBox的实例方法是有意义的。
顺便说一句，如果attributes列表中的对象数量很大，最好使用字典：
class ToyBox(object):
def __init__(self):
self.attributes = dict()
def add_attr(self, a):
if a.key not in self.attributes:
self.attributes[a.key] = a
def __str__(self):
return ','.join(map(str,self.attributes.values()))注意:如果您希望保持添加对象的顺序，请使用OrderedDict代替
https://stackoverflow.com/questions/33895930
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