From fa157db84c00e88b3ec0b40384d42914574d6d32 2012-04-09 22:11:30
From: MinRK <benjaminrk@gmail.com>
Date: 2012-04-09 22:11:30
Subject: [PATCH] clear_output implies '\r' for terminal frontends

---

diff --git a/IPython/core/display.py b/IPython/core/display.py
index c44f3d0..37c6021 100644
--- a/IPython/core/display.py
+++ b/IPython/core/display.py
@@ -17,6 +17,8 @@ Authors:
 # Imports
 #-----------------------------------------------------------------------------
 
+from __future__ import print_function
+
 from xml.dom import minidom
 
 from .displaypub import (
@@ -496,6 +498,16 @@ def clear_output(stdout=True, stderr=True, other=True):
         (e.g. figures,images,HTML, any result of display()).
     """
     from IPython.core.interactiveshell import InteractiveShell
-    InteractiveShell.instance().display_pub.clear_output(
-        stdout=stdout, stderr=stderr, other=other,
-    )
+    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()
+        
diff --git a/IPython/core/displaypub.py b/IPython/core/displaypub.py
index cfcf939..388757e 100644
--- a/IPython/core/displaypub.py
+++ b/IPython/core/displaypub.py
@@ -30,6 +30,7 @@ Authors:
 from __future__ import print_function
 
 from IPython.config.configurable import Configurable
+from IPython.utils import io
 
 #-----------------------------------------------------------------------------
 # Main payload class
@@ -99,14 +100,20 @@ 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
+    def clear_output(self, stdout=True, stderr=True, other=True):
+        """Clear the output of the cell receiving output."""
+        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):
diff --git a/IPython/zmq/zmqshell.py b/IPython/zmq/zmqshell.py
index 21baabf..7c42f88 100644
--- a/IPython/zmq/zmqshell.py
+++ b/IPython/zmq/zmqshell.py
@@ -81,8 +81,15 @@ 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