clear_output implies '\r' for terminal frontends

IPython/core/display.py

@@ -17,6 +17,8 b' Authors:'
 # Imports
 #-----------------------------------------------------------------------------
 
+from __future__ import print_function
+
 from xml.dom import minidom
 
 from .displaypub import (
@@ -496,6 +498,16 b' def clear_output(stdout=True, stderr=True, other=True):'
         (e.g. figures,images,HTML, any result of display()).
     """
     from IPython.core.interactiveshell import InteractiveShell
+    if InteractiveShell.initialized():
     InteractiveShell.instance().display_pub.clear_output(
         stdout=stdout, stderr=stderr, other=other,
     )
+    else:
+        from IPython.utils import io
+        if stdout:
+            print('\033[2K\r', file=io.stdout, end='')
+            io.stdout.flush()
+        if stderr:
+            print('\033[2K\r', file=io.stderr, end='')
+            io.stderr.flush()
+        

IPython/core/displaypub.py

@@ -30,6 +30,7 b' Authors:'
 from __future__ import print_function
 
 from IPython.config.configurable import Configurable
+from IPython.utils import io
 
 #-----------------------------------------------------------------------------
 # Main payload class
@@ -99,14 +100,20 b' class DisplayPublisher(Configurable):'
             arbitrary key, value pairs that frontends can use to interpret
             the data.
         """
-        from IPython.utils import io
+
         # The default is to simply write the plain text data using io.stdout.
         if data.has_key('text/plain'):
             print(data['text/plain'], file=io.stdout)
 
         def clear_output(self, stdout=True, stderr=True, other=True):
             """Clear the output of the cell receiving output."""
-            pass
+        if stdout:
+            print('\033[2K\r', file=io.stdout, end='')
+            io.stdout.flush()
+        if stderr:
+            print('\033[2K\r', file=io.stderr, end='')
+            io.stderr.flush()
+            
 
 
 def publish_display_data(source, data, metadata=None):

IPython/zmq/zmqshell.py

@@ -81,8 +81,15 b' class ZMQDisplayPublisher(DisplayPublisher):'
         )
 
     def clear_output(self, stdout=True, stderr=True, other=True):
-        self._flush_streams()
         content = dict(stdout=stdout, stderr=stderr, other=other)
+        
+        if stdout:
+            print('\r', file=sys.stdout, end='')
+        if stderr:
+            print('\r', file=sys.stderr, end='')
+        
+        self._flush_streams()
+        
         self.session.send(
             self.pub_socket, u'clear_output', content,
             parent=self.parent_header