[registry/select_best] move from 'debug_call' to select_listener observator pattern

1 files changed, 31 insertions, 19 deletions

diff --git a/logilab/common/registry.py b/logilab/common/registry.py
index 27b72b6..cfebe17 100644
--- a/logilab/common/registry.py
+++ b/logilab/common/registry.py
@@ -263,6 +263,7 @@ class Registry(dict):
     def __init__(self, debugmode):
         super(Registry, self).__init__()
         self.debugmode = debugmode
+        self._select_listeners = []
 
     def __getitem__(self, name):
         """return the registry (list of implementation objects) associated to
@@ -399,6 +400,17 @@ class Registry(dict):
                 continue
             yield obj
 
+    def add_select_best_listener(self, listener):
+        """
+        Add a listener to the list of one parameters callables (function/method)
+        that will be called everytime the selection Registry._select_best is
+        done and they will recieve a dict of the following form::
+
+          {"all_objects": [], "end_score": 0, "winners": [], "winner": None or winner,
+          "self": self, "args": args, "kwargs": kwargs, }
+        """
+        self._select_listeners.append(listener)
+
     def _select_best(self, objects, *args, **kwargs):
         """return an instance of the most specific object according
         to parameters
@@ -407,30 +419,29 @@ class Registry(dict):
         it's costly when searching objects using `possible_objects`
         (e.g. searching for hooks).
 
-        An optional argument `debug_callback` can be passed, it will be called
-        once the selection is done and will return a dict of the following form::
+        Every callable stored in Registry._select_listeners will be called
+        once the selection is done and will recieve a dict of the following form::
 
           {"all_objects": [], "end_score": 0, "winners": [], "winner": None or winner,
           "self": self, "args": args, "kwargs": kwargs, }
         """
 
-        debug_callback = kwargs.pop('debug_callback', None)
-
-        debug_registry_select_best = {
-            "all_objects": [],
-            "end_score": 0,
-            "winners": [],
-            "self": self,
-            "args": args,
-            "kwargs": kwargs,
-        }
+        if self._select_listeners:
+            select_best_report = {
+                "all_objects": [],
+                "end_score": 0,
+                "winners": [],
+                "self": self,
+                "args": args,
+                "kwargs": kwargs,
+            }
 
         score, winners = 0, None
         for obj in objects:
             objectscore = obj.__select__(obj, *args, **kwargs)
 
-            if debug_callback:
-                debug_registry_select_best["all_objects"].append({"object": obj, "score": objectscore})
+            if self._select_listeners:
+                select_best_report["all_objects"].append({"object": obj, "score": objectscore})
 
             if objectscore > score:
                 score, winners = objectscore, [obj]
@@ -438,11 +449,12 @@ class Registry(dict):
             elif objectscore > 0 and objectscore == score:
                 winners.append(obj)
 
-        if debug_callback:
-            debug_registry_select_best["winners"] = winners.copy() if winners else []
-            debug_registry_select_best["winner"] = winners[0] if winners else winners
-            debug_registry_select_best["end_score"] = score
-            debug_callback(debug_registry_select_best)
+        if self._select_listeners:
+            select_best_report["winners"] = winners.copy() if winners else []
+            select_best_report["winner"] = winners[0] if winners else winners
+            select_best_report["end_score"] = score
+            for listener in self._select_listeners:
+                listener(select_best_report)
 
         if winners is None:
             return None