C struct to Python
debatem1 at gmail.com
Tue Nov 30 20:16:24 CET 2010
On Tue, Nov 30, 2010 at 10:57 AM, Eric Frederich
<eric.frederich at gmail.com> wrote:
> I am not sure how to proceed.
> I am writing a Python interface to a C library.
> The C library uses structures.
> I was looking at the struct module but struct.unpack only seems to
> deal with data that was packed using struct.pack or some other buffer.
> All I have is the struct itself, a pointer in C.
> Is there a way to unpack directly from a memory address?
> Right now on the C side of things I can create a buffer of the struct
> data like so...
> MyStruct ms;
> unsigned char buffer[sizeof(MyStruct) + 1];
> memcpy(buffer, &ms, sizeof(MyStruct));
> return Py_BuildValue("s#", buffer, sizeof(MyStruct));
> Then on the Python side I can unpack it using struct.unpack.
> I'm just wondering if I need to jump through these hoops of packing it
> on the C side or if I can do it directly from Python.
ctypes sounds like a possible solution, although if you're already
writing a C extension it might be better practice to just write a
Python object that wraps your C struct appropriately. If you're not
wedded to the C extension, though, I've had very good luck writing C
interfaces with with ctypes and a few useful decorators , .
Others prefer Cython, which I like for speed but which sometimes
seems to get in my way when I'm trying to interface with existing
code. There's a good, if somewhat dated, overview of a few other
More information about the Python-list