Load entrypoint plugins before builtin and contrib.

Allows for overriding builtin plugins via entrypoint method.

Signed-off-by: Mark Reid <[email protected]>

src/py-opentimelineio/opentimelineio/plugins/manifest.py

@@ -202,10 +202,10 @@ def load_manifest():
 
     The order of loading (and precedence) is:
 
-       1. manifests specfied via the ``OTIO_PLUGIN_MANIFEST_PATH`` variable
-       2. builtin plugin manifest
-       3. contrib plugin manifest
-       4. ``setuptools.pkg_resources`` based plugin manifests
+       1. Manifests specified via the ``OTIO_PLUGIN_MANIFEST_PATH`` variable
+       2. Entrypoint based plugin manifests
+       3. Builtin plugin manifest
+       4. Contrib plugin manifest
     """
 
     result = Manifest()
@@ -242,22 +242,6 @@ def load_manifest():
         plugin_manifest = manifest_from_file(builtin_manifest_path)
         result.extend(plugin_manifest)
 
-    # the contrib plugin manifest (located in the opentimelineio_contrib package)
-    try:
-        import opentimelineio_contrib as otio_c
-
-        contrib_manifest_path = os.path.join(
-            os.path.dirname(inspect.getsourcefile(otio_c)),
-            "adapters",
-            "contrib_adapters.plugin_manifest.json"
-        )
-        if os.path.abspath(contrib_manifest_path) not in result.source_files:
-            contrib_manifest = manifest_from_file(contrib_manifest_path)
-            result.extend(contrib_manifest)
-
-    except ImportError:
-        pass
-
     # setuptools.pkg_resources based plugins
     if pkg_resources:
         for plugin in pkg_resources.iter_entry_points(
@@ -324,6 +308,22 @@ def load_manifest():
         #        available?
         pass
 
+    # the contrib plugin manifest (located in the opentimelineio_contrib package)
+    try:
+        import opentimelineio_contrib as otio_c
+
+        contrib_manifest_path = os.path.join(
+            os.path.dirname(inspect.getsourcefile(otio_c)),
+            "adapters",
+            "contrib_adapters.plugin_manifest.json"
+        )
+        if os.path.abspath(contrib_manifest_path) not in result.source_files:
+            contrib_manifest = manifest_from_file(contrib_manifest_path)
+            result.extend(contrib_manifest)
+
+    except ImportError:
+        pass
+
     # force the schemadefs to load and add to schemadef module namespace
     for s in result.schemadefs:
         s.module()