Warn about deprecation at runtime (#15)

* Document deprecation of this package.
* Document suggested alternatives.
* Warn at runtime about the deprecation status of the package so developers using it can get a hint even when they don't read the readme of this package.

src/tempstorage/TemporaryStorage.py

@@ -20,6 +20,7 @@
 """
 import bisect
 from logging import getLogger
+import warnings
 import time
 
 from ZODB import POSException
@@ -84,6 +85,14 @@ def __init__(self, name='TemporaryStorage'):
 
         _conflict_cache_maxage -- age at whic conflict cache items are GC'ed
         """
+        deprecation_warning = """\
+DEPRECATED: Usage of the package tempstorage is deprecated, as it is known to randomly lose data.
+Especially on Zope 4. For details see https://github.com/zopefoundation/tempstorage/issues/8
+and https://github.com/zopefoundation/tempstorage
+"""
+        LOG.warning(deprecation_warning)
+        warnings.warn(deprecation_warning, DeprecationWarning)
+
         BaseStorage.__init__(self, name)
 
         self._index = {}