5 files changed, 72 insertions, 8 deletions
diff --git a/src/mailman/docs/NEWS.rst b/src/mailman/docs/NEWS.rst
index 64df34ef1..b9720b960 100644
--- a/src/mailman/docs/NEWS.rst
+++ b/src/mailman/docs/NEWS.rst
@@ -73,18 +73,21 @@ Interfaces
    `IMailingList` to an `IBanManager` to manage the bans for a specific
    mailing list.  To manage the global bans, adapt ``None``.
 
-Integration
------------
- * Added support for Postfix `relay_domains` setting for better virtual domain
-   support.  Contributed by Jimmy Bergman.
-
 Commands
 --------
  * `bin/mailman aliases` loses the `--output`, `--format`, and `--simple`
    arguments, and adds a `--directory` argument.  This is necessary to support
    the Postfix `relay_domains` support.
  * `bin/mailman start` was passing the wrong relative path to its runner
-   subprocesses when -C was given.  LP: #982551
+   subprocesses when -C was given.  (LP: #982551)
+
+Other
+-----
+ * Added support for Postfix `relay_domains` setting for better virtual domain
+   support.  Contributed by Jimmy Bergman.
+ * Two new events are triggered on membership changes: `SubscriptionEvent`
+   when a new member joins a mailing list, and an `UnsubscriptionEvent` when a
+   member leaves a mailing list.  (LP: #1047286)
 
 Bugs
 ----
diff --git a/src/mailman/interfaces/member.py b/src/mailman/interfaces/member.py
index 997338835..815bda2d4 100644
--- a/src/mailman/interfaces/member.py
+++ b/src/mailman/interfaces/member.py
@@ -26,10 +26,13 @@ __all__ = [
     'DeliveryStatus',
     'IMember',
     'MemberRole',
+    'MembershipChangeEvent',
     'MembershipError',
     'MembershipIsBannedError',
     'MissingPreferredAddressError',
     'NotAMemberError',
+    'SubscriptionEvent',
+    'UnsubscriptionEvent',
     ]
 
 
@@ -74,6 +77,34 @@ class MemberRole(Enum):
 
 
 
+class MembershipChangeEvent:
+    """Base class for subscription/unsubscription events."""
+
+    def __init__(self, mlist, member):
+        self.mlist = mlist
+        self.member = member
+
+
+class SubscriptionEvent(MembershipChangeEvent):
+    """Event which gets triggered when a user joins a mailing list."""
+
+    def __str__(self):
+        return '{0} joined {1}'.format(self.member.address, self.mlist.list_id)
+
+
+class UnsubscriptionEvent(MembershipChangeEvent):
+    """Event which gets triggered when a user leaves a mailing list.
+
+    One thing to keep in mind: because the IMember is deleted when the
+    unsubscription happens, this event actually gets triggered just before the
+    member is unsubscribed.
+    """
+
+    def __str__(self):
+        return '{0} left {1}'.format(self.member.address, self.mlist.list_id)
+
+
+
 class MembershipError(MailmanError):
     """Base exception for all membership errors."""
 
diff --git a/src/mailman/model/docs/membership.rst b/src/mailman/model/docs/membership.rst
index 3286bfe6e..f257f25ce 100644
--- a/src/mailman/model/docs/membership.rst
+++ b/src/mailman/model/docs/membership.rst
@@ -315,3 +315,26 @@ Now her membership reflects the new address.
     >>> for m in bee.members.members:
     ...     print m.member_id.int, m.mailing_list.list_id, m.address.email
     7 bee.example.com gperson@example.com
+
+
+Events
+======
+
+An event is triggered when a new member is subscribed to a mailing list.
+::
+
+    >>> from mailman.testing.helpers import event_subscribers
+    >>> def handle_event(event):
+    ...     print event
+
+    >>> cat = create_list('cat@example.com')
+    >>> herb = user_manager.create_address('herb@example.com')
+    >>> with event_subscribers(handle_event):
+    ...     member = cat.subscribe(herb)
+    herb@example.com joined cat.example.com
+
+An event is triggered when a member is unsubscribed from a mailing list.
+
+    >>> with event_subscribers(handle_event):
+    ...     member.unsubscribe()
+    herb@example.com left cat.example.com
diff --git a/src/mailman/model/mailinglist.py b/src/mailman/model/mailinglist.py
index 2c55540be..324e1a1c8 100644
--- a/src/mailman/model/mailinglist.py
+++ b/src/mailman/model/mailinglist.py
@@ -33,6 +33,7 @@ from storm.locals import (
     TimeDelta, Unicode)
 from urlparse import urljoin
 from zope.component import getUtility
+from zope.event import notify
 from zope.interface import implementer
 
 from mailman.config import config
@@ -50,7 +51,8 @@ from mailman.interfaces.mailinglist import (
     IAcceptableAlias, IAcceptableAliasSet, IMailingList, Personalization,
     ReplyToMunging)
 from mailman.interfaces.member import (
-    AlreadySubscribedError, MemberRole, MissingPreferredAddressError)
+    AlreadySubscribedError, MemberRole, MissingPreferredAddressError,
+    SubscriptionEvent)
 from mailman.interfaces.mime import FilterType
 from mailman.interfaces.nntp import NewsgroupModeration
 from mailman.interfaces.user import IUser
@@ -493,6 +495,7 @@ class MailingList(Model):
                         subscriber=subscriber)
         member.preferences = Preferences()
         store.add(member)
+        notify(SubscriptionEvent(self, member))
         return member
 
 
diff --git a/src/mailman/model/member.py b/src/mailman/model/member.py
index 76fe2f992..c189983b9 100644
--- a/src/mailman/model/member.py
+++ b/src/mailman/model/member.py
@@ -27,6 +27,7 @@ __all__ = [
 from storm.locals import Int, Reference, Unicode
 from storm.properties import UUID
 from zope.component import getUtility
+from zope.event import notify
 from zope.interface import implementer
 
 from mailman.core.constants import system_preferences
@@ -36,7 +37,8 @@ from mailman.database.types import Enum
 from mailman.interfaces.action import Action
 from mailman.interfaces.address import IAddress
 from mailman.interfaces.listmanager import IListManager
-from mailman.interfaces.member import IMember, MemberRole, MembershipError
+from mailman.interfaces.member import (
+    IMember, MemberRole, MembershipError, UnsubscriptionEvent)
 from mailman.interfaces.user import IUser, UnverifiedAddressError
 from mailman.interfaces.usermanager import IUserManager
 from mailman.utilities.uid import UniqueIDFactory
@@ -186,5 +188,7 @@ class Member(Model):
     @dbconnection
     def unsubscribe(self, store):
         """See `IMember`."""
+        # Yes, this must get triggered before self is deleted.
+        notify(UnsubscriptionEvent(self.mailing_list, self))
         store.remove(self.preferences)
         store.remove(self)