fix bug:

 * gradient_clipping_threshold should be allowed to set with parameter-grain

python/paddle/trainer_config_helpers/attrs.py

@@ -19,34 +19,34 @@ __all__ = [
 
 
 def convert_and_compare(x, Type):
-    """                                                                                                                                                                                                
-    Convert x to be the same type as Type and then convert back to                                                                                                                                      
-    check whether there is a loss of information                                                                                                                                                        
-    :param x: object to be checked                                                                                                                                                                      
-    :param Type: target type to check x over                                                                                                                                                           
-    
+    """
+    Convert x to be the same type as Type and then convert back to
+    check whether there is a loss of information
+    :param x: object to be checked
+    :param Type: target type to check x over
+
     """
     return type(x)(Type(x)) == x
 
 
 def is_compatible_with(x, Type):
-    """                                                                                                                                                                                                
-    Check if x has a type compatible with Type                                                                                                                                                         
-    :param x: object to be checked                                                                                                                                                                     
-    :param Type: target type to check x over                                                                                                                                                           
-    
+    """
+    Check if x has a type compatible with Type
+    :param x: object to be checked
+    :param Type: target type to check x over
+
     """
     if type(x) == Type:
         return True
     try:
         if float == Type or int == Type:
-            # avoid those types that can be converted to float/int but not very                                                                                                                            
-            # meaningful and  could potentially lead to error                                                                                                                                              
-            # i.e., str and bool typed value should not be used for initializing float/int variable                                                                                                        
+            # avoid those types that can be converted to float/int but not very
+            # meaningful and  could potentially lead to error
+            # i.e., str and bool typed value should not be used for initializing float/int variable
             if not isinstance(x, str) and not isinstance(x, bool):
                 return convert_and_compare(x, Type)
         elif bool == Type:
-            # should not use string type to initialize bool variable                                                                                                                                   
+            # should not use string type to initialize bool variable
             if not isinstance(x, str):
                 return convert_and_compare(x, Type)
         else:
@@ -88,6 +88,10 @@ class ParameterAttribute(object):
     :type learning_rate: float or None
     :param momentum: The parameter momentum. None means use global value.
     :type momentum: float or None
+    :param gradient_clipping_threshold: gradient clipping threshold. If gradient
+                                        value larger than some value, will be
+                                        clipped.
+    :type gradient_clipping_threshold: float
     :param sparse_update: Enable sparse update for this parameter. It will
                           enable both local and remote sparse update.
     :type sparse_update: bool
@@ -104,6 +108,7 @@ class ParameterAttribute(object):
                  l2_rate=None,
                  learning_rate=None,
                  momentum=None,
+                 gradient_clipping_threshold=None,
                  sparse_update=False):
         # initialize strategy.
         if is_static:
@@ -152,6 +157,11 @@ class ParameterAttribute(object):
             self.attr['sparse_update'] = True
             self.attr['sparse_remote_update'] = True
 
+        if gradient_clipping_threshold is not None and \
+                is_compatible_with(gradient_clipping_threshold, float):
+            self.attr['gradient_clipping_threshold'] = \
+                gradient_clipping_threshold
+
     def set_default_parameter_name(self, name):
         """
         Set default parameter name. If parameter not set, then will use default