diff -r 000000000000 -r b97547f5f1fa common/__init__.py
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/common/__init__.py	Wed Nov 05 15:52:50 2008 +0100
@@ -0,0 +1,52 @@
+"""Common subpackage of cubicweb : defines library functions used both on the
+hg stserver side and on the client side
+
+:organization: Logilab
+:copyright: 2001-2008 LOGILAB S.A. (Paris, FRANCE), all rights reserved.
+:contact: http://www.logilab.fr/ -- mailto:contact@logilab.fr
+"""
+
+from logilab.common.adbh import FunctionDescr
+
+from cubicweb._exceptions import * # bw compat
+
+from rql.utils import register_function, iter_funcnode_variables
+
+class COMMA_JOIN(FunctionDescr):
+    supported_backends = ('postgres', 'sqlite',)
+    rtype = 'String'
+    
+    @classmethod
+    def st_description(cls, funcnode):
+        return ', '.join(term.get_description()
+                         for term in iter_funcnode_variables(funcnode))
+    
+register_function(COMMA_JOIN)  # XXX do not expose?
+
+
+class CONCAT_STRINGS(COMMA_JOIN):
+    aggregat = True
+    
+register_function(CONCAT_STRINGS) # XXX bw compat
+
+class GROUP_CONCAT(CONCAT_STRINGS):
+    supported_backends = ('mysql', 'postgres', 'sqlite',)
+    
+register_function(GROUP_CONCAT)
+
+
+class LIMIT_SIZE(FunctionDescr):
+    supported_backends = ('postgres', 'sqlite',)
+    rtype = 'String'
+    
+    @classmethod
+    def st_description(cls, funcnode):
+        return funcnode.children[0].get_description()
+    
+register_function(LIMIT_SIZE)
+
+
+class TEXT_LIMIT_SIZE(LIMIT_SIZE):
+    supported_backends = ('mysql', 'postgres', 'sqlite',)
+    
+register_function(TEXT_LIMIT_SIZE)