From b70b5db9d8c7f4291dfdb80fe55b28c494a2e442 2013-03-21 20:51:46
From: MinRK <benjaminrk@gmail.com>
Date: 2013-03-21 20:51:46
Subject: [PATCH] use canning hook in dependent

allows the dependency function to be called even before the real task arguments are unpacked.
---

diff --git a/IPython/parallel/controller/dependency.py b/IPython/parallel/controller/dependency.py
index a5b1dfe..02ee8fa 100644
--- a/IPython/parallel/controller/dependency.py
+++ b/IPython/parallel/controller/dependency.py
@@ -59,10 +59,12 @@ class dependent(object):
         self.df = df
         self.dargs = dargs
         self.dkwargs = dkwargs
-
-    def __call__(self, *args, **kwargs):
+    
+    def check_dependency(self):
         if self.df(*self.dargs, **self.dkwargs) is False:
             raise UnmetDependency()
+    
+    def __call__(self, *args, **kwargs):
         return self.f(*args, **kwargs)
     
     if not py3compat.PY3:
diff --git a/IPython/utils/pickleutil.py b/IPython/utils/pickleutil.py
index bfff04c..a19c1c9 100644
--- a/IPython/utils/pickleutil.py
+++ b/IPython/utils/pickleutil.py
@@ -64,7 +64,7 @@ class CannedObject(object):
         obj = self.obj
         for key in self.keys:
             setattr(obj, key, uncan(getattr(obj, key), g))
-
+        
         if self.hook:
             self.hook = uncan(self.hook, g)
             self.hook(obj, g)
@@ -308,6 +308,11 @@ def uncan_sequence(obj, g=None):
     else:
         return obj
 
+def _uncan_dependent_hook(dep, g=None):
+    dep.check_dependency()
+    
+def can_dependent(obj):
+    return CannedObject(obj, keys=('f', 'df'), hook=_uncan_dependent_hook)
 
 #-------------------------------------------------------------------------------
 # API dictionaries
@@ -316,7 +321,7 @@ def uncan_sequence(obj, g=None):
 # These dicts can be extended for custom serialization of new objects
 
 can_map = {
-    'IPython.parallel.dependent' : lambda obj: CannedObject(obj, keys=('f','df')),
+    'IPython.parallel.dependent' : can_dependent,
     'numpy.ndarray' : CannedArray,
     FunctionType : CannedFunction,
     bytes : CannedBytes,