python - 在python中解包对象变量

Question

我在想是否有某种方法可以解包对象属性。通常这样做涉及一系列：

self.x = x
self.y = y
... #etc.

但是应该可以做得更好。

我正在考虑类似的事情：

def __init__(self,x,y,z):
  self.(x,y,z) = x,y,z

或者可能：

用 x,y,z 解包（自我）

甚至功能如下：

def __init__(self,x,y,z):
  unpack(self,x,y,z)

有任何想法吗？还是有一些更蟒蛇的方式来做到这一点？

Answer 1

您可能想要使用namedtuple，这正是您想要的：

来自官方 Python 文档的代码示例：

Point = namedtuple('Point', ['x', 'y'], verbose=True)

上面的代码等价于：

class Point(tuple):
    'Point(x, y)'

    __slots__ = ()

    _fields = ('x', 'y')

    def __new__(_cls, x, y):
        'Create a new instance of Point(x, y)'
        return _tuple.__new__(_cls, (x, y))

    @classmethod
    def _make(cls, iterable, new=tuple.__new__, len=len):
        'Make a new Point object from a sequence or iterable'
        result = new(cls, iterable)
        if len(result) != 2:
            raise TypeError('Expected 2 arguments, got %d' % len(result))
        return result

    def __repr__(self):
        'Return a nicely formatted representation string'
        return 'Point(x=%r, y=%r)' % self

    def _asdict(self):
        'Return a new OrderedDict which maps field names to their values'
        return OrderedDict(zip(self._fields, self))

    def _replace(_self, **kwds):
        'Return a new Point object replacing specified fields with new values'
        result = _self._make(map(kwds.pop, ('x', 'y'), _self))
        if kwds:
            raise ValueError('Got unexpected field names: %r' % kwds.keys())
        return result

    def __getnewargs__(self):
        'Return self as a plain tuple.   Used by copy and pickle.'
        return tuple(self)

    __dict__ = _property(_asdict)

    def __getstate__(self):
        'Exclude the OrderedDict from pickling'
        pass

    x = _property(_itemgetter(0), doc='Alias for field number 0')

    y = _property(_itemgetter(1), doc='Alias for field number 1')

以下是如何使用它：

>>> p = Point(11, y=22)     # instantiate with positional or keyword arguments
>>> p[0] + p[1]             # indexable like the plain tuple (11, 22)
33
>>> x, y = p                # unpack like a regular tuple
>>> x, y
(11, 22)
>>> p.x + p.y               # fields also accessible by name
33
>>> p                       # readable __repr__ with a name=value style
Point(x=11, y=22)

来源： http ://docs.python.org/2/library/collections.html#namedtuple-factory-function-for-tuples-with-named-fields

值得一提的是，namedtuple它只是一个普通类，您可以创建一个继承自它的类。

Answer 2

我很确定你可以这样做：self.x, self.y, self.z = x, y, z

Answer 3

定义像 unpack(self,x,y,z) 这样的函数可能不是一个好主意，因为该函数不够通用（对象的组合是在运行时定义的）

此处解释了基于属性名称实例化变量的更通用的方法 http://code.activestate.com/recipes/286185-automatically-initializing-instance-variables-from/

Answer 4

class Blahblah:
def __init__(self, *args, **kwargs):
    def unpack(vars_name, args, kwargs): #Cant be acceded for some instance in this place
        nonlocal self
        for i, var in enumerate(vars_name):
            exec(f"self.{var}={args[i]}")
        for key, value in kwargs.items():
            exec(f"self.{key}={value}")
    
    #You must add some validator for de length of args before the next code in this place
    
    vars_for_self = ["a","b","c"]
    unpack(vars_for_self, args, kwargs)
    
    del vars_for_self, args, kwargs, unpack #For clean vars in the class instance
            
    

    #First ways to check de self vars creation
    #print(self.__dict__)

    #Second way to check
    #print(locals()["self"].__dict__)

#Your other methods go here

签到结果

if __name__== "__main__":
#And the last way
  c = Blahblah(3,4,5, x=6,y=7,z=0)
  #print(c.a)
  #print(c.x)

  print(c.__dict__)
  print(vars(Blahblah.__dict__["__init__"]))