MemcachedKeyLengthError: Key length is > 250

Fix for python-memcached MemcachedKeyLengthError

from django.core.cache.backends import memcached
from django.utils.encoding import smart_str

Simple Django cache backend overrides for dealing with python-memcached
differences between cmemcache.

For Django 1.2. All methods except `set_many` and `delete_many` will work for Django 1.1

Use by pointing to it in settings, for example:

CACHE_BACKEND = myproject.contrib.thisfile://
class CacheClass(memcached.CacheClass):
    "Filter key through `_smart_key` before sending to backend for all cases"
    def __init__(self, server, params):
        super(CacheClass,self).__init__(server, params)
    def add(self, key, value, timeout=0):
        return super(CacheClass, self).add(self._smart_key(key), value, timeout)
    def get(self, key):
        return super(CacheClass, self).get(self._smart_key(key))
    def set(self, key, value, timeout=0):
        super(CacheClass, self).set(self._smart_key(key), value, timeout)
    def delete(self, key):
        super(CacheClass, self).delete(self._smart_key(key))
    def _smart_key(self, key):
        "Truncate all keys to 250 or less and remove control characters"
        if key:
            return smart_str(''.join([c for c in key
                                        if ord(c) > 32 and ord(c) != 127]))[:250]
        return key

coded by nessus