传递Python的对象作为函数的参数

Question

1. There is a function from a DLL (C language) link("parameters", &connection); which takes a string parameter and initializes a connection.

2. There is a function connect(connection) , where the connection - the object, initialized with a call to link() .

Question: how to pass Python connection object function Connect () as an argument?

from ctypes import *
mydll = CDLL (link.dll)
# How define the connection object?
top = link ("localhost: 5412", connection)
top = connect (connection)

Answer 1

I believe that winapi handle is 32 bits long, but you might need to ensure that it be that the true length. If you are not using connection in any other way, maybe you can do this:

connection_t = ctypes.c_uint32

link = mydll.link
link.argtypes=(ctypes.c_char_p, ctypes.POINTER(connection_t) )
connect = mydll.connect
connect.argtypes=(connection_t,)
...
connection = connection_t()
link ("localhost: 5412", ctypes.byref(connection))
...

Note that:

• You might use another type as the opaque equivalent to HANDLE, as long as it has the same byte-length. Even better, you can "protect" your created connection _t type by inheriting instead of just assigning.