Store cachefile strategy on file; not generator

The file can appeal to the generator for the value, but it shouldn't
require it; it just does that as a convenience.

imagekit/cachefiles/__init__.py

@@ -15,7 +15,7 @@ class ImageCacheFile(BaseIKFile, ImageFile):
     to be deferred until the time that the cache file strategy requires it.
 
     """
-    def __init__(self, generator, name=None, storage=None, cachefile_backend=None):
+    def __init__(self, generator, name=None, storage=None, cachefile_backend=None, cachefile_strategy=None):
         """
         :param generator: The object responsible for generating a new image.
         :param name: The filename
@@ -23,6 +23,8 @@ class ImageCacheFile(BaseIKFile, ImageFile):
             file.
         :param cachefile_backend: The object responsible for managing the
             state of the file.
+        :param cachefile_strategy: The object responsible for handling events
+            for this file.
 
         """
         self.generator = generator
@@ -43,6 +45,12 @@ class ImageCacheFile(BaseIKFile, ImageFile):
             or getattr(generator, 'cachefile_backend', None)
             or get_singleton(settings.IMAGEKIT_DEFAULT_CACHEFILE_BACKEND,
                              'cache file backend'))
+        self.cachefile_strategy = (
+            cachefile_strategy
+            or getattr(generator, 'cachefile_strategy', None)
+            or get_singleton(settings.IMAGEKIT_DEFAULT_CACHEFILE_STRATEGY,
+                             'cache file strategy')
+        )
 
         super(ImageCacheFile, self).__init__(storage=storage)
 

imagekit/registry.py

@@ -48,7 +48,7 @@ class GeneratorRegistry(object):
         # FIXME: I guess this means you can't register functions?
         if generator.__class__ in self._generators.values():
             # Only invoke the strategy method for registered generators.
-            call_strategy_method(generator, 'before_access', file=file)
+            call_strategy_method(file, 'before_access')
 
 
 class SourceGroupRegistry(object):
@@ -105,7 +105,7 @@ class SourceGroupRegistry(object):
 
         for spec in specs:
             file = ImageCacheFile(spec)
-            call_strategy_method(spec, callback_name, file=file)
+            call_strategy_method(file, callback_name)
 
 
 class CacheFileRegistry(object):

imagekit/utils.py

@@ -124,11 +124,11 @@ def generate(generator):
     return File(content)
 
 
-def call_strategy_method(generator, method_name, *args, **kwargs):
-    strategy = getattr(generator, 'cachefile_strategy', None)
+def call_strategy_method(file, method_name):
+    strategy = getattr(file, 'cachefile_strategy', None)
     fn = getattr(strategy, method_name, None)
     if fn is not None:
-        fn(*args, **kwargs)
+        fn(file)
 
 
 def sanitize_cache_key(key):