Merge branch 'release/2.4.0'

Author: ayalash

.travis.yml

@@ -4,6 +4,7 @@ python:
 - '2.7'
 - '3.5'
 - '3.6'
+- '3.7'
 - pypy
 install:
 - pip install -U pip

doc/advanced.rst

@@ -183,6 +183,24 @@ Handlers can be registered with *tokens*. A token is anything that supports equa
 
 
 
+Registration Guard
+------------------
+
+Sometimes it is desirable to have a way to enable/disable registrations dynamically. For this purpose, gossip supports guards on handlers. A guard is a callable object, returning whether or not the handler should be triggered
+
+.. code-block:: python
+
+    >>> class State(object): enabled=False
+    >>> state = State()
+		>>> @gossip.register('guarded_hook', guard=lambda: state.enabled)
+		... def handler1():
+		...     print('Called')
+    >>> gossip.trigger('guarded_hook')
+    >>> state.enabled = True
+    >>> gossip.trigger('guarded_hook')
+    Called
+
+
 Getting Hooks by Name
 ---------------------
 

doc/changelog.rst

@@ -1,6 +1,8 @@
 Changelog
 =========
 
+* :release:`2.4.0 <03-09-2019>`
+* :feature:`39` Add ``guard`` argument to ``register``
 * :release:`2.3.1 <28-08-2018>`
 * :bug:`36` Ensure ``define_hook`` handles hook kwargs even if it already being defined
 * :bug:`30` Switch to PBR

gossip/hooks.py

@@ -224,7 +224,8 @@ def trigger(self, kwargs, tags=None):
             while True:
                 any_resolved = False
                 for registration in list(registrations):
-                    if not registration.valid:
+                    if not registration.is_active():
+                        _logger.trace("Skipping {} because it is inactive", registration)
                         continue
                     if not registration.has_tags(tags):
                         continue
@@ -343,7 +344,8 @@ def define(hook_name, **kwargs):
     return returned
 
 
-def register(func=None, hook_name=None, token=None, tags=None, needs=None, provides=None, reentrant=True, toggles_on=None, toggles_off=None, priority=0):
+def register(func=None, hook_name=None, token=None, tags=None, needs=None, provides=None, reentrant=True,
+             toggles_on=None, toggles_off=None, priority=0, guard=None):
     """Registers a new function to a hook
 
     :param hook_name: full name of hook to register to
@@ -374,13 +376,14 @@ def register(func=None, hook_name=None, token=None, tags=None, needs=None, provi
             toggles_on=toggles_on,
             toggles_off=toggles_off,
             priority=priority,
+            guard=guard,
         )
     assert hook_name is not None
     registration = get_or_create_hook(
         hook_name).register(
             func, token=token, tags=tags, needs=needs, provides=provides, reentrant=reentrant,
             toggles_on=toggles_on, toggles_off=toggles_off,
-            priority=priority,
+            priority=priority, guard=guard,
         )
     assert registration
     return func

gossip/registration.py

@@ -13,10 +13,12 @@
 
 class Registration(object):
 
-    def __init__(self, func, hook, token=None, tags=None, needs=None, provides=None, reentrant=True, toggles_on=None, toggles_off=None, priority=0):
+    def __init__(self, func, hook, token=None, tags=None, needs=None, provides=None, reentrant=True, toggles_on=None,
+                 toggles_off=None, priority=0, guard=None):
         super(Registration, self).__init__()
 
         assert not (toggles_off is not None and toggles_on is not None), 'Cannot specify both toggles_on and toggles_off'
+        assert (guard is None) or callable(guard), "Registration 'guard' argument must be callable if specified"
         self.id = next(_registration_id)
         self.hook = hook
         self.func = func
@@ -33,6 +35,7 @@ def __init__(self, func, hook, token=None, tags=None, needs=None, provides=None,
         self._toggles_on = toggles_on
         self._toggles_off = toggles_off
         self._priority = priority
+        self._guard = guard
 
     def get_priority(self):
         return self._priority
@@ -55,7 +58,11 @@ def unregister(self):
             assert self.hook is None
 
     def is_active(self):
-        return self.hook is not None
+        if (self.hook is None) or (not self.valid):
+            return False
+        if self._guard is None:
+            return True
+        return self._guard()
 
     def is_being_called(self):
         return self._is_being_called
@@ -91,7 +98,7 @@ def _check_toggle(self):
         return True
 
     def __repr__(self):
-        return repr(self.func)
+        return "<{}: {}>".format(self.__class__.__name__, self.func)
 
 
 def _normalize_deps(deps):

setup.cfg

@@ -4,6 +4,7 @@ classifiers =
     Programming Language :: Python :: 2.7
     Programming Language :: Python :: 3.5
     Programming Language :: Python :: 3.6
+    Programming Language :: Python :: 3.7
 description = Signaling and hooking library
 license = BSD3
 author = Rotem Yaari