Split MemoizedZipManifests from ZipManifests. Ref #154.

pkg_resources.py

@@ -1533,22 +1533,8 @@ empty_provider = EmptyProvider()
 
 class ZipManifests(dict):
     """
-    Memoized zipfile manifests.
+    zip manifest builder
     """
-    manifest_mod = collections.namedtuple('manifest_mod', 'manifest mtime')
-
-    def load(self, path):
-        """
-        Load a manifest at path or return a suitable manifest already loaded.
-        """
-        path = os.path.normpath(path)
-        mtime = os.stat(path).st_mtime
-
-        if path not in self or self[path].mtime != mtime:
-            manifest = self.build(path)
-            self[path] = self.manifest_mod(manifest, mtime)
-
-        return self[path].manifest
 
     @classmethod
     def build(cls, path):
@@ -1569,6 +1555,28 @@ class ZipManifests(dict):
             )
             return dict(items)
 
+    load = build
+
+
+class MemoizedZipManifests(ZipManifests):
+    """
+    Memoized zipfile manifests.
+    """
+    manifest_mod = collections.namedtuple('manifest_mod', 'manifest mtime')
+
+    def load(self, path):
+        """
+        Load a manifest at path or return a suitable manifest already loaded.
+        """
+        path = os.path.normpath(path)
+        mtime = os.stat(path).st_mtime
+
+        if path not in self or self[path].mtime != mtime:
+            manifest = self.build(path)
+            self[path] = self.manifest_mod(manifest, mtime)
+
+        return self[path].manifest
+
 
 class ContextualZipFile(zipfile.ZipFile):
     """