pretty: don't hardcode names for counter/deque/etc subclasses

ask for `obj.__class__.__name__`

IPython/lib/pretty.py

@@ -791,7 +791,7 b' _singleton_pprinters = dict.fromkeys(map(id, [None, True, False, Ellipsis,'
 
 
 def _defaultdict_pprint(obj, p, cycle):
-    name = 'defaultdict'
+    name = obj.__class__.__name__
     with p.group(len(name) + 1, name + '(', ')'):
         if cycle:
             p.text('...')
@@ -802,7 +802,7 b' def _defaultdict_pprint(obj, p, cycle):'
             p.pretty(dict(obj))
 
 def _ordereddict_pprint(obj, p, cycle):
-    name = 'OrderedDict'
+    name = obj.__class__.__name__
     with p.group(len(name) + 1, name + '(', ')'):
         if cycle:
             p.text('...')
@@ -810,7 +810,7 b' def _ordereddict_pprint(obj, p, cycle):'
             p.pretty(list(obj.items()))
 
 def _deque_pprint(obj, p, cycle):
-    name = 'deque'
+    name = obj.__class__.__name__
     with p.group(len(name) + 1, name + '(', ')'):
         if cycle:
             p.text('...')
@@ -819,7 +819,7 b' def _deque_pprint(obj, p, cycle):'
 
 
 def _counter_pprint(obj, p, cycle):
-    name = 'Counter'
+    name = obj.__class__.__name__
     with p.group(len(name) + 1, name + '(', ')'):
         if cycle:
             p.text('...')

IPython/lib/tests/test_pretty.py

@@ -350,9 +350,12 b' def test_collections_deque():'
         nt.assert_equal(pretty.pretty(obj), expected)
 
 def test_collections_counter():
+    class MyCounter(Counter):
+        pass
     cases = [
         (Counter(), 'Counter()'),
         (Counter(a=1), "Counter({'a': 1})"),
+        (MyCounter(a=1), "MyCounter({'a': 1})"),
     ]
     for obj, expected in cases:
         nt.assert_equal(pretty.pretty(obj), expected)