[Checkins] SVN: martian/trunk/src/martian/ Make sure registrations happens only once.

[Martijn Faassen]

Log message for revision 76811:
  Make sure registrations happens only once.
  

Changed:
  U   martian/trunk/src/martian/README.txt
  U   martian/trunk/src/martian/core.py

-=-
Modified: martian/trunk/src/martian/README.txt
===================================================================
--- martian/trunk/src/martian/README.txt	2007-06-19 19:49:26 UTC (rev 76810)
+++ martian/trunk/src/martian/README.txt	2007-06-19 19:58:42 UTC (rev 76811)
@@ -936,6 +936,47 @@
   >>> multi_grokker.grok('ColorGrokker', ColorGrokker)
   True
 
+Executing meta grokkers only once
+---------------------------------
+
+In case of ``ClassGrokker`` and all other grokkers that are grokked
+by meta grokkers, we only want the grokking to occur once even if
+the same module (or package) is grokked twice::
+
+  >>> class TestOnce(object):
+  ...   pass
+  >>> executed = []
+  >>> class somemodule(FakeModule):
+  ...   class TestGrokker(ClassGrokker):
+  ...     component_class = TestOnce
+  ...     def grok(self, name, obj):
+  ...        executed.append(name)
+  ...        return True
+  >>> somemodule = fake_import(somemodule)
+  >>> module_grokker = ModuleGrokker(MetaMultiGrokker())
+
+Let's grok the module once::
+
+  >>> module_grokker.grok('somemodule', somemodule)
+  True
+
+Let's grok it twice::
+  
+  >>> module_grokker.grok('somemodule', somemodule)
+  True
+
+Even though we have grokked it twice, it is still only registered once. We
+can show this by actually having it grok a ``TestOnce`` subclass::
+
+  >>> class anothermodule(FakeModule):
+  ...   class TestSub(TestOnce):
+  ...      pass
+  >>> anothermodule = fake_import(anothermodule)
+  >>> module_grokker.grok('anothermodule', anothermodule)
+  True
+  >>> executed
+  ['TestSub']
+
 Priority
 --------
 

Modified: martian/trunk/src/martian/core.py
===================================================================
--- martian/trunk/src/martian/core.py	2007-06-19 19:49:26 UTC (rev 76810)
+++ martian/trunk/src/martian/core.py	2007-06-19 19:58:42 UTC (rev 76811)
@@ -58,9 +58,8 @@
 
         # sort grokkers by priority
         grokkers = sorted(self.grokkers(name, module),
-                          key=lambda (grokker, name, obj): grokker.priority)
-        # reverse so highest priority happens first
-        grokkers.reverse()
+                          key=lambda (grokker, name, obj): grokker.priority,
+                          reverse=True)
         
         for g, name, obj in grokkers:
             grokked = g.grok(name, obj, **kw)
@@ -103,8 +102,10 @@
     def register(self, grokker):
         key = grokker.component_class
         grokkers = self._grokkers.setdefault(key, [])
-        if grokker not in grokkers:
-            grokkers.append(grokker)
+        for g in grokkers:
+            if g.__class__ is grokker.__class__:
+                return
+        grokkers.append(grokker)
 
     def clear(self):
         self._grokkers = {}
@@ -136,7 +137,8 @@
         self.clear()
 
     def register(self, grokker):
-        self._grokkers.append(grokker)
+        if grokker not in self._grokkers:
+            self._grokkers.append(grokker)
 
     def clear(self):
         self._grokkers = []