Re: [ctypes-users] Casting, Pointers, and OOR

[Mark G. <mar...@sy...>]

I went back to double check and it looks like I was keeping a
reference to the CFUNCTYPE not the callback function.  I added this
and my errors appeared to go away.  Thanks for the help and sorry for
the easy mistake.
--Mark

On 11/28/07, Lenard Lindstrom <le...@te...> wrote:
> You do keep the callback alive with a Python reference, right?
>
> Lenard
>
> Mark Guagenti wrote:
> > I went ahead and built a debug version of python 2.5.1 and ran a non
> > wxpython version of my script and got it to fail as well.  The
> > exception appears to be occurring at:
> > _ctypes_d.pyd!ffi_closure_SYSV(ffi_closure * closure=0x0153ff00, int *
> > argp=0x0098278c)  Line 243 + 0x1b
> >
> > --Mark
> >
> > On 11/28/07, Mark Guagenti <mar...@sy...> wrote:
> >
> >> On 11/28/07, Lenard Lindstrom <le...@te...> wrote:
> >>
> >>> Also, calling d.onData does not return control to the main thread, if
> >>> that is the intension. Execution leaves the callback thread only when
> >>> the callback returns. So it could be a threading problem with wx.
> >>>
> >> I thought wx.CallAfter would ensure that processing the data would
> >> occur in the main thread of the application which in my case is the wx
> >> GUI thread?
> >>
> >> I added the check you suggest and it appears that I am not getting a
> >> null pointer.  Here is an updated cooked down example:
> >>
> >> #Functype for dllCallback passed to DLL
> >> recvType = ctypes.CFUNCTYPE(None, ctypes.c_ubyte, ctypes.c_void_p)
> >>
> >> class DllWrap(object):
> >>  ...
> >>  def dllCallback(self, dev, msg):
> >>    if not msg:
> >>      print "ERROR no msg!"
> >>      return
> >>
> >>    data = ctypes.cast(msg, ctypes.POINTER(ctypes.c_char))
> >>
> >>    if not data:
> >>      print "ERROR no data!"
> >>      return
> >>
> >>   len = int(binascii.hexlify(data[4]), 16)
> >>   b.onData(data[:len])
> >>   dll.Free(dev, msg)
> >>
> >> class B(wx.grid.Grid):
> >>  ...
> >>  def onData(self, data):
> >>   wx.CallAfter(self.processData, data)
> >>
> >>  def processData(self, data):
> >>   ... #Add data to grid
> >>
> >>
> >
> >
>
>
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