Have a look at pickle docs, you will see that a class needs a
getstate,setstate methods to
support pickling. Large/complex instances of classes won't pickle out
of the box think about
classes like request handlers have many subobjects and pickle wouldn't
know how to deal with
this.
Rgds
Tim
P.S. I am not sure why you would want to cache a request handler in
the first place though.
On Dec 2, 3:08 am, hawkett <[EMAIL PROTECTED]> wrote:
> It occurred to me that pickle may have looked *everywhere* else, and
> __builtin__ is just the last place it looked, which explains the
> error. So perhaps I just need to install my class definition
> *anywhere* that pickle can find it. Still the question stands though -
> what's the best approach to achieve what I am trying to do? Thanks.
>
> On Dec 1, 5:26 pm, hawkett <[EMAIL PROTECTED]> wrote:
>
> > Hi,
>
> > This might be a generic pythin question, but since I'm running into
> > an issue on GAE with memcache, this is probably a good place to ask.
>
> > I've got the following code
>
> > opGlobals = {}
> > exec(requestHandlerCode, opGlobals)
> > requestHandler = opGlobals["RequestHandler"]()
> > memcache.add(key="requestHandler", value=requestHandler)
>
> > where 'requestHandlerCode' from the second line is just a python class
> > definition retrieved from a TextProperty in the datastore. Lines 1-3
> > execute fine, and I can call methods on the class instantiated in line
> > 3. However, trying to put the instance into memcache as in line 4
> > generates the following error -
>
> > PicklingError: Can't pickle <class __builtin__.RequestHandler at
> > 0x17ef0c0>: it's not found as __builtin__.RequestHandler
>
> > Which is fine - I understand that it needs to be able to find the
> > class definition in order to pickle/unpickle the object - what I'm not
> > sure of is the best approach to resolving the problem. I could put
> > the code in memcache, but then I'd be compiling and instantiating it
> > every request, which is no good.
>
> > The obvious options seem to be -
>
> > 1. Install the class definition in __builtin__ so pickle does know
> > what to do with it (feels like a hack?)
> > 2. Tell pickle to also look elsewhere for the information it needs
>
> > If someone who knows python better than I do could point me in the
> > right direction, that would be great. Cheers,
>
> > Colin
>
>
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