Python 在 ctypes.Structure 中动态设置 _fields_
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Setting _fields_ dynamically in ctypes.Structure
提问by
Reading the documentation here, I see that you can use ctypes.Structure as follows :-
阅读此处的文档，我看到您可以按如下方式使用 ctypes.Structure ：-
>>> class Int(Structure):
... _fields_ = [("first_16", c_int, 16),
... ("second_16", c_int, 16)]
...
>>> print Int
Would it be possible for me to create such a class by using a list that I decide upon dynamically? For eg, something along the lines of :-
我是否可以通过使用我动态决定的列表来创建这样的类？例如，类似的东西：-
def int_factory(fields):
int_class = get_int_class(fields) # This returns a class object with _fields_ set to fields
return int_class
def user(values=[1,2]):
int_class = int_factory(int_fields)
i = int_class(values[0], values[1])
Would it be possible to do this?
有可能做到这一点吗？
采纳答案by CristiFati
In the example below:
在下面的例子中：
- int_factorygenerates the Intclass
- userreturns an Intinstance with first_16set to 1 and second_16set to 2
- int_factory生成Int类
- 用户返回一个int实例，其中first_16设置为 1，second_16设置为 2
code.py:
代码.py：
#!/usr/bin/env python3
import sys
from ctypes import Structure, \
c_int
def int_factory(fields):
return type("Int", (Structure,), {"_fields_": fields})
def user(values=[1, 2]):
int_fields = (("first_16", c_int, 16), ("second_16", c_int, 16)) # This is just an example to illustrate your class definition. int_fields can be generated dynamically.
int_class = int_factory(int_fields)
int_obj = int_class(*values)
return int_obj
def print_int_obj_data(int_obj):
print("Type: {:}\n_fields_: {:}".format(int_obj.__class__.__name__, int_obj._fields_))
for field in int_obj._fields_:
print(" {:}: {:}".format(field[0], getattr(int_obj, field[0])))
def main():
int0 = user()
print_int_obj_data(int0)
if __name__ == "__main__":
print("Python {:s} on {:s}\n".format(sys.version, sys.platform))
main()
Output:
输出：
e:\Work\Dev\StackOverflow\q030799760>"e:\Work\Dev\VEnvs\py27x64_test\Scripts\python.exe" code.py Python 2.7.13 (v2.7.13:a06454b1afa1, Dec 17 2016, 20:53:40) [MSC v.1500 64 bit (AMD64)] on win32 Type: Int _fields_: (('first_16', <class 'ctypes.c_long'>, 16), ('second_16', <class 'ctypes.c_long'>, 16)) first_16: 1 second_16: 2
e:\Work\Dev\StackOverflow\q030799760>"e:\Work\Dev\VEnvs\py27x64_test\Scripts\python.exe" code.py Python 2.7.13 (v2.7.13:a06454b1afa1, Dec 17 2016, 20:53:40) [MSC v.1500 64 bit (AMD64)] on win32 Type: Int _fields_: (('first_16', <class 'ctypes.c_long'>, 16), ('second_16', <class 'ctypes.c_long'>, 16)) first_16: 1 second_16: 2
