change the interface of build_sampler and build_assigner, replace default_args with **kwargs

mmdet/core/bbox/assign_sampling.py

@@ -3,23 +3,23 @@ import mmcv
 from . import assigners, samplers
 
 
-def build_assigner(cfg, default_args=None):
+def build_assigner(cfg, **kwargs):
     if isinstance(cfg, assigners.BaseAssigner):
         return cfg
     elif isinstance(cfg, dict):
         return mmcv.runner.obj_from_dict(
-            cfg, assigners, default_args=default_args)
+            cfg, assigners, default_args=kwargs)
     else:
         raise TypeError('Invalid type {} for building a sampler'.format(
             type(cfg)))
 
 
-def build_sampler(cfg, default_args=None):
+def build_sampler(cfg, **kwargs):
     if isinstance(cfg, samplers.BaseSampler):
         return cfg
     elif isinstance(cfg, dict):
         return mmcv.runner.obj_from_dict(
-            cfg, samplers, default_args=default_args)
+            cfg, samplers, default_args=kwargs)
     else:
         raise TypeError('Invalid type {} for building a sampler'.format(
             type(cfg)))