Add model based wd skip support. Improve cross version compat of optimizer factory. Fix huggingface#247

Author: rwightman

timm/optim/optim_factory.py

@@ -41,7 +41,10 @@ def create_optimizer(args, model, filter_bias_and_bn=True):
     opt_lower = args.opt.lower()
     weight_decay = args.weight_decay
     if weight_decay and filter_bias_and_bn:
-        parameters = add_weight_decay(model, weight_decay)
+        skip = {}
+        if hasattr(model, 'no_weight_decay'):
+            skip = model.no_weight_decay
+        parameters = add_weight_decay(model, weight_decay, skip)
         weight_decay = 0.
     else:
         parameters = model.parameters()
@@ -50,9 +53,9 @@ def create_optimizer(args, model, filter_bias_and_bn=True):
         assert has_apex and torch.cuda.is_available(), 'APEX and CUDA required for fused optimizers'
 
     opt_args = dict(lr=args.lr, weight_decay=weight_decay)
-    if args.opt_eps is not None:
+    if hasattr(args, 'opt_eps') and args.opt_eps is not None:
         opt_args['eps'] = args.opt_eps
-    if args.opt_betas is not None:
+    if hasattr(args, 'opt_betas') and args.opt_betas is not None:
         opt_args['betas'] = args.opt_betas
 
     opt_split = opt_lower.split('_')