1 files changed, 80 insertions, 60 deletions

diff --git a/Mailman/pipeline/avoid_duplicates.py b/Mailman/pipeline/avoid_duplicates.py
index 2c52a7781..78a65c8c8 100644
--- a/Mailman/pipeline/avoid_duplicates.py
+++ b/Mailman/pipeline/avoid_duplicates.py
@@ -23,71 +23,91 @@ has already received a copy, we either drop the message, add a duplicate
 warning header, or pass it through, depending on the user's preferences.
 """
 
+__metaclass__ = type
+__all__ = ['AvoidDuplicates']
+
+
 from email.Utils import getaddresses, formataddr
+from zope.interface import implements
+
 from Mailman.configuration import config
+from Mailman.i18n import _
+from Mailman.interfaces import IHandler
+
 
 COMMASPACE = ', '
 
 
 
-def process(mlist, msg, msgdata):
-    recips = msgdata.get('recips')
-    # Short circuit
-    if not recips:
-        return
-    # Seed this set with addresses we don't care about dup avoiding.
-    listaddrs = set((mlist.posting_address,
-                     mlist.bounces_address,
-                     mlist.owner_address,
-                     mlist.request_address))
-    explicit_recips = listaddrs.copy()
-    # Figure out the set of explicit recipients
-    cc_addresses = {}
-    for header in ('to', 'cc', 'resent-to', 'resent-cc'):
-        addrs = getaddresses(msg.get_all(header, []))
-        header_addresses = dict((addr, formataddr((name, addr)))
-                                for name, addr in addrs
-                                if addr)
-        if header == 'cc':
-            # Yes, it's possible that an address is mentioned in multiple CC
-            # headers using different names.  In that case, the last real name
-            # will win, but that doesn't seem like such a big deal.  Besides,
-            # how else would you chose?
-            cc_addresses.update(header_addresses)
-        # Ignore the list addresses for purposes of dup avoidance.
-        explicit_recips |= set(header_addresses)
-    # Now strip out the list addresses
-    explicit_recips -= listaddrs
-    if not explicit_recips:
-        # No one was explicitly addressed, so we can't do any dup collapsing
-        return
-    newrecips = set()
-    for r in recips:
-        # If this recipient is explicitly addressed...
-        if r in explicit_recips:
-            send_duplicate = True
-            # If the member wants to receive duplicates, or if the recipient
-            # is not a member at all, they will get a copy.
-            # header.
-            member = mlist.members.get_member(r)
-            if member and not member.receive_list_copy:
-                send_duplicate = False
-            # We'll send a duplicate unless the user doesn't wish it.  If
-            # personalization is enabled, the add-dupe-header flag will add a
-            # X-Mailman-Duplicate: yes header for this user's message.
-            if send_duplicate:
-                msgdata.setdefault('add-dup-header', set()).add(r)
+class AvoidDuplicates:
+    """If the user wishes it, do not send duplicates of the same message."""
+
+    implements(IHandler)
+
+    name = 'avoid-duplicates'
+    description = _('Suppress some duplicates of the same message.')
+
+    def process(self, mlist, msg, msgdata):
+        """See `IHandler`."""
+        recips = msgdata.get('recips')
+        # Short circuit
+        if not recips:
+            return
+        # Seed this set with addresses we don't care about dup avoiding.
+        listaddrs = set((mlist.posting_address,
+                         mlist.bounces_address,
+                         mlist.owner_address,
+                         mlist.request_address))
+        explicit_recips = listaddrs.copy()
+        # Figure out the set of explicit recipients.
+        cc_addresses = {}
+        for header in ('to', 'cc', 'resent-to', 'resent-cc'):
+            addrs = getaddresses(msg.get_all(header, []))
+            header_addresses = dict((addr, formataddr((name, addr)))
+                                    for name, addr in addrs
+                                    if addr)
+            if header == 'cc':
+                # Yes, it's possible that an address is mentioned in multiple
+                # CC headers using different names.  In that case, the last
+                # real name will win, but that doesn't seem like such a big
+                # deal.  Besides, how else would you chose?
+                cc_addresses.update(header_addresses)
+            # Ignore the list addresses for purposes of dup avoidance.
+            explicit_recips |= set(header_addresses)
+        # Now strip out the list addresses.
+        explicit_recips -= listaddrs
+        if not explicit_recips:
+            # No one was explicitly addressed, so we can't do any dup
+            # collapsing
+            return
+        newrecips = set()
+        for r in recips:
+            # If this recipient is explicitly addressed...
+            if r in explicit_recips:
+                send_duplicate = True
+                # If the member wants to receive duplicates, or if the
+                # recipient is not a member at all, they will get a copy.
+                # header.
+                member = mlist.members.get_member(r)
+                if member and not member.receive_list_copy:
+                    send_duplicate = False
+                # We'll send a duplicate unless the user doesn't wish it.  If
+                # personalization is enabled, the add-dupe-header flag will
+                # add a X-Mailman-Duplicate: yes header for this user's
+                # message.
+                if send_duplicate:
+                    msgdata.setdefault('add-dup-header', set()).add(r)
+                    newrecips.add(r)
+                elif r in cc_addresses:
+                    del cc_addresses[r]
+            else:
+                # Otherwise, this is the first time they've been in the recips
+                # list.  Add them to the newrecips list and flag them as
+                # having received this message.
                 newrecips.add(r)
-            elif r in cc_addresses:
-                del cc_addresses[r]
-        else:
-            # Otherwise, this is the first time they've been in the recips
-            # list.  Add them to the newrecips list and flag them as having
-            # received this message.
-            newrecips.add(r)
-    # Set the new list of recipients.  XXX recips should always be a set.
-    msgdata['recips'] = list(newrecips)
-    # RFC 2822 specifies zero or one CC header
-    if cc_addresses:
-        del msg['cc']
-        msg['CC'] = COMMASPACE.join(cc_addresses.values())
+        # Set the new list of recipients.  XXX recips should always be a set.
+        msgdata['recips'] = list(newrecips)
+        # RFC 2822 specifies zero or one CC header
+        if cc_addresses:
+            del msg['cc']
+            msg['CC'] = COMMASPACE.join(cc_addresses.values())