python类中结构体 结构体 python

python中定义结构体通过继承_ctypes中的Structure类，标准写法如下：

c:

struct beer_recipe
{
    int  amt_barley;
    int  amt_water;
};
struct beer_recipe
{
    int  amt_barley;
    int  amt_water;
};

python：

class beer_recipe(Structure):
    _fields_ = [
                ("amt_barley",c_int),
                ("amt_water",c_int),
                ]
class beer_recipe(Structure):
    _fields_ = [
                ("amt_barley",c_int),
                ("amt_water",c_int),
                ]

看一个libsvm中的例子：

class svm_node(Structure):
	_names = ["index", "value"]
	_types = [c_int, c_double]
	_fields_ = genFields(_names, _types)

	def __str__(self):
		return '%d:%g' % (self.index, self.value)
class svm_node(Structure):
	_names = ["index", "value"]
	_types = [c_int, c_double]
	_fields_ = genFields(_names, _types)

	def __str__(self):
		return '%d:%g' % (self.index, self.value)

def genFields(names, types):
	return list(zip(names, types))
def genFields(names, types):
	return list(zip(names, types))

svm_node实际上就是这样一个东西：

_fields_ = [
                ("index",c_int),
                ("value",c_double),
                ]
_fields_ = [
                ("index",c_int),
                ("value",c_double),
                ]

即一个index对应一个value，分别是int和double类型。只不过是用了zip这样的少见的函数。