Removed dependency of memcache module for DistributedRamCache plugin

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@11046 20353a03-c40f-0410-a6d1-a30d3c3de9de

product/ERP5/Tool/CacheTool.py

@@ -38,6 +38,11 @@ from Products.ERP5Type.CachePlugins.RamCache import RamCache
 from Products.ERP5Type.CachePlugins.DistributedRamCache import DistributedRamCache
 from Products.ERP5Type.CachePlugins.SQLCache import SQLCache
 
+## try to import needed modules for cache plugins
+try:     
+  import memcache
+except ImportError:  
+  pass
 
 class CacheTool(BaseTool):
   """ Caches tool wrapper for ERP5 """
@@ -67,21 +72,30 @@ class CacheTool(BaseTool):
       rd[cache_scope]['cache_plugins'] = []
       rd[cache_scope]['cache_params'] = {}
       for cp in cf.getCachePluginList():
+	cache_obj = None
         cp_meta_type = cp.meta_type
         if cp_meta_type == 'ERP5 Ram Cache Plugin':
           cache_obj = RamCache()
         elif cp_meta_type == 'ERP5 Distributed Ram Cache Plugin':
-          cache_obj = DistributedRamCache({'server':cp.getServer()})
+	  ## even thougn we have such plugin in ZODB that doens't mean
+	  ## we have corresponding memcache module installed
+	  if 'memcache' in globals().keys():
+            cache_obj = DistributedRamCache({'server':cp.getServer()})
+          else:
+	    ## we don't have memcache python module installed 
+	    ## thus we can't use DistributedRamCache plugin
+	    cache_obj = None
         elif cp_meta_type == 'ERP5 SQL Cache Plugin':
           ## use connection details from 'erp5_sql_transactionless_connection' ZMySLQDA object
           connection_string = self.erp5_sql_transactionless_connection.connection_string
           kw = self.parseDBConnectionString(connection_string)
           kw['cache_table_name'] = cp.getCacheTableName()
           cache_obj = SQLCache(kw)
-        ## set cache expire check interval
-        cache_obj.cache_expire_check_interval = cp.getCacheExpireCheckInterval() 
-        rd[cache_scope]['cache_plugins'].append(cache_obj)
-        rd[cache_scope]['cache_params']['cache_duration'] = cf.getCacheDuration() 
+	if cache_obj:
+          ## set cache expire check interval
+          cache_obj.cache_expire_check_interval = cp.getCacheExpireCheckInterval() 
+          rd[cache_scope]['cache_plugins'].append(cache_obj)
+          rd[cache_scope]['cache_params']['cache_duration'] = cf.getCacheDuration() 
     return rd
 
   ##