Add print_test_value_by_default option

theano/compile/debugmode.py

@@ -764,7 +764,7 @@ def debugprint(r, prefix='', depth=-1, done=None, print_type=False,
                 outer_id_str = get_id_str(outer_r.owner)
             else:
                 outer_id_str = get_id_str(outer_r)
-            print('%s%s %s%s -> %s' % (prefix, r, id_str, type_str,
+            print('%s%s %s%s -> %s' % (prefix, r.__str_name__(), id_str, type_str,
                                        outer_id_str), file=file)
         else:
             # this is an input variable
@@ -772,7 +772,7 @@ def debugprint(r, prefix='', depth=-1, done=None, print_type=False,
             if smap:
                 data = " " + str(smap.get(r, ''))
             id_str = get_id_str(r)
-            print('%s%s %s%s%s' % (prefix, r, id_str,
+            print('%s%s %s%s%s' % (prefix, r.__str_name__(), id_str,
                                    type_str, data),
                   file=file)
 

theano/configdefaults.py

@@ -644,6 +644,14 @@ AddConfigVar(
     in_c_key=False)
 
 
+AddConfigVar(
+    'print_test_value_by_default',
+    ("If 'True', Theano will override the '__str__' method of its "
+     "variables to also print the tag.test_value when this is available."),
+    BoolParam(False),
+    in_c_key=False)
+
+
 AddConfigVar('compute_test_value_opt',
              ("For debugging Theano optimization only."
               " Same as compute_test_value, but is used"

theano/gof/graph.py

@@ -12,6 +12,7 @@ from copy import copy
 from itertools import count
 
 import theano
+from theano import config
 from theano.gof import utils
 from six import string_types, integer_types, iteritems
 from theano.misc.ordered_set import OrderedSet
@@ -394,6 +395,17 @@ class Variable(Node):
         """
         WRITEME
 
+        """
+        if config.print_test_value_by_default:
+            if self.__get_test_value__() is not None:
+                return '\n'.join([self.__str_name__(),
+                                 self.__get_test_value__()])
+        return self.__str_name__()
+
+    def __str_name__(self):
+        """
+        WRITEME
+
         """
         if self.name is not None:
             return self.name
@@ -406,6 +418,12 @@ class Variable(Node):
         else:
             return "<%s>" % str(self.type)
 
+    def __get_test_value__(self):
+        try:
+            return repr(self.tag.test_value)
+        except AttributeError:
+            return None
+
     def __repr__(self):
         return str(self)