[英]Python Classes: adding dynamic attributes to methods
Say we have a class: 假设我们有一个班级:
class Foo (object):
... def __init__(self,d):
... self.d=d
... def return_d(self):
... return self.d
... and a dict: ......和一个字典:
d={'k1':1,'k2':2}
... and an instance: ......和一个实例:
inst=Foo(d)
Is there a way to dynamically add attributes to return_d
so: 有没有办法动态地向
return_d
添加属性,所以:
inst.return_d.k1
would return 1? inst.return_d.k1
会返回1吗?
You'd need to do two things: declare return_d
as an attribute or property, and return a dict-like object that allows attribute access for dictionary keys. 您需要做两件事:将
return_d
声明为属性或属性,并返回一个类似于dict的对象,该对象允许对字典键进行属性访问。 The following would work: 以下将有效:
class AttributeDict(dict):
__getattr__ = dict.__getitem__
class Foo (object):
def __init__(self,d):
self.d=d
@property
def return_d(self):
return AttributeDict(self.d)
Short demo: 简短演示:
>>> foo = Foo({'k1':1,'k2':2})
>>> foo.return_d.k1
1
The property
decorator turns methods into attributes, and the __getattr__
hook allows the AttributeDict
class to look up dict keys via attribute access (the .
operator). property
装饰器将方法转换为属性, __getattr__
钩子允许AttributeDict
类通过属性访问( .
运算符)查找dict键。
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