[Python-Dev] [python 2.7] a question about exporting a new method to socket object

[Guido van Rossum]

Technically this list isn't the right place, but you probably are
bitten by the duplication of functionality in Lib/socket.py. There's a
list of methods at the top of that file, _socketmethods.

But you really shouldn't be asking here -- this list is for changes to
Python, not using or hacking it. (Try StackOverflow for that.)

--Guido

On Thu, Jun 20, 2013 at 10:18 PM, Ani Sinha <ani at aristanetworks.com> wrote:
> Hi python devs :
>
> As a part of exploring an idea, I am trying to add a new method to the
> python socket object. Here's what I have been trying to do (the patch may be
> whitespace damaged so please bear with me) :
>
>
> Index: Python-2.7/Modules/socketmodule.c
> ===================================================================
> --- Python-2.7.orig/Modules/socketmodule.c
> +++ Python-2.7/Modules/socketmodule.c
> @@ -126,6 +126,7 @@ makefile([mode, [bufsize]]) -- return a
>  recv(buflen[, flags]) -- receive data\n\
>  recv_into(buffer[, nbytes[, flags]]) -- receive data (into a buffer)\n\
>  recvfrom(buflen[, flags]) -- receive data and sender\'s address\n\
> +arecvfrom(buflen[, flags]) -- same as recvfrom \n\
>  recvfrom_into(buffer[, nbytes, [, flags])\n\
>    -- receive data and sender\'s address (into a buffer)\n\
>  sendall(data[, flags]) -- send all data\n\
> @@ -468,6 +469,13 @@ static PyTypeObject sock_type;
>  #define IS_SELECTABLE(s) ((s)->sock_fd < FD_SETSIZE || s->sock_timeout <=
> 0.0)
>  #endif
>
> @@ -2620,6 +2802,58 @@ PyDoc_STRVAR(recvfrom_doc,
>  \n\
>  Like recv(buffersize, flags) but also return the sender's address info.");
>
> +static PyObject *
> +sock_arecvfrom(PySocketSockObject *s, PyObject *args)
> +{
> +    return sock_recvfrom(s,args);
> +}
> +
> +PyDoc_STRVAR(arecvfrom_doc,
> +"arecvfrom(buffersize[, flags]) -> (data, address info)\n\
> +\n\
> + experimental stuff");
>
>  /* s.recvfrom_into(buffer[, nbytes [,flags]]) method */
>
> @@ -2963,6 +3197,8 @@ static PyMethodDef sock_methods[] = {
>                        recv_into_doc},
>      {"recvfrom",          (PyCFunction)sock_recvfrom, METH_VARARGS,
>                        recvfrom_doc},
> +    {"arecvfrom",          (PyCFunction)sock_arecvfrom, METH_VARARGS,
> +                      arecvfrom_doc},
>      {"recvfrom_into",  (PyCFunction)sock_recvfrom_into, METH_VARARGS |
> METH_KEYWORDS,
>                        recvfrom_into_doc},
>      {"send",              (PyCFunction)sock_send, METH_VARARGS,
>
>
> When I compile this and run a simple script like the following that uses
> arecvfrom() :
>
> sock = socket.socket( socket.PF_PACKET, socket.SOCK_RAW )
> sock.bind( ( intf, ETH_P_ALL ) )
>
> (pkt,dontcare) = dst.arecvfrom( 500, socket.MSG_DONTWAIT )
>
> I get this exception :
>
> AttributeError: '_socketobject' object has no attribute 'arecvfrom'
>
> So what am I doing wrong? How do I export this new socket method?
>
> any help/pointer will be greatly appreciated.
>
> cheers,
> ani
>
> --
> Ani
>
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-- 
--Guido van Rossum (python.org/~guido)