Merge pull request #711 from Haichao-Zhang/input_types_check

adding input type check for python data provider

Author: reyoung

python/paddle/trainer/PyDataProvider2.py

@@ -202,6 +202,24 @@ def loop_check(callback, item):
         for each in item:
             callback(each)
 
+class CheckInputTypeWrapper(object):
+    def __init__(self, generator, input_types, logger):
+        self.generator = generator
+        self.input_types = input_types
+        self.logger = logger
+
+    def __call__(self, obj, filename): 
+       for items in self.generator(obj, filename):
+           try:
+               # dict type is required for input_types when item is dict type 
+               assert (isinstance(items, dict) and \
+                       not isinstance(self.input_types, dict))==False
+               yield items
+           except AssertionError as e:
+               self.logger.error(
+                    "%s type is required for input type but got %s" %
+                    (repr(type(items)), repr(type(self.input_types))))
+               raise
 
 def provider(input_types=None,
              should_shuffle=None,
@@ -355,6 +373,9 @@ def __init__(self, file_list, **kwargs):
                 if use_dynamic_order:
                     self.generator = InputOrderWrapper(self.generator,
                                                        self.input_order)
+                else:
+                    self.generator = CheckInputTypeWrapper(self.generator, self.slots,
+                                                           self.logger) 
                 if self.check:
                     self.generator = CheckWrapper(self.generator, self.slots,
                                                   check_fail_continue,