如何在python中定义C-Enumeration类型

Question

我在C中有一个枚举数据类型。我应该如何在python-ctypes中声明它？我想让这个枚举变量成为一个结构的一部分，并且这个结构的赋值将通过memmove完成。分配后，我想显示结构中每个变量的值，以及我想要显示枚举字符串的枚举类型。

Answer 1

The Enumeration class suggested by Raj Kumar被打破，因为它需要运行__init__以在变量中设置新值，因此如果在C端更改了值，则不可用。下面是其一个固定的版本：

class EnumerationType(type(c_uint)): 
    def __new__(metacls, name, bases, dict): 
     if not "_members_" in dict: 
      _members_ = {} 
      for key, value in dict.items(): 
       if not key.startswith("_"): 
        _members_[key] = value 

      dict["_members_"] = _members_ 
     else: 
      _members_ = dict["_members_"] 

     dict["_reverse_map_"] = { v: k for k, v in _members_.items() } 
     cls = type(c_uint).__new__(metacls, name, bases, dict) 
     for key,value in cls._members_.items(): 
      globals()[key] = value 
     return cls 

    def __repr__(self): 
     return "<Enumeration %s>" % self.__name__ 

class CEnumeration(c_uint): 
    __metaclass__ = EnumerationType 
    _members_  = {} 

    def __repr__(self): 
     value = self.value 
     return "<%s.%s: %d>" % (
      self.__class__.__name__, 
      self._reverse_map_.get(value, '(unknown)'), 
      value 
     ) 

    def __eq__(self, other): 
     if isinstance(other, (int, long)): 
      return self.value == other 

     return type(self) == type(other) and self.value == other.value 

现在一个可以声明一个CEnumeration：

class EBoolean(CEnumeration): 
    FALSE = 0 
    TRUE = 1 

并使用它：

class HeaderStruct(Structure): 
    _fields_ = [("param1", EBoolean), 
       ("param2", c_uint)] 

实例：

>>> header = HeaderStruct() 
>>> header.param1 
<EBoolean.FALSE: 0> 
>>> memmove(addressof(header), b'\x01', 1) # write LSB 0x01 in the boolean 
>>> header.param1 
<EBoolean.TRUE: 1> 
>>> header.param1 == EBoolean.TRUE 
True 
>>> header.param1 == 1 # as a special case compare against ints 
True 
>>> header.param1.value 
1L 

Answer 2

的Antti哈帕拉做了一个幻想ic工作回答！但是，当我将Python 3.2.2用于我认为值得注意的事情时，我遇到了一些小问题。相反的：

class CEnumeration(c_uint): 
    __metaclass__ = EnumerationType 
    _members_  = {} 

你需要做的：

class CEnumeration(c_uint, metaclass = EnumerationType): 
    _members_  = {} 

而且，int和long一直在Python 3，以便统一：

def __eq__(self, other): 
     if isinstance(other, (int, long)): 
      return self.value == other 

     return type(self) == type(other) and self.value == other.value 

变为：

def __eq__(self, other): 
     if isinstance(other, int): 
      return self.value == other 

     return type(self) == type(other) and self.value == other.value