making %clear a native magic

IPython/core/completerlib.py

@@ -181,7 +181,6 b' def quick_completer(cmd, completions):'
 
     get_ipython().set_hook('complete_command',do_complete, str_key = cmd)
 
-
 def module_completion(line):
     """
     Returns a list containing the completion possibilities for an import line.
@@ -316,3 +315,7 b' def cd_completer(self, event):'
         raise TryNext
 
     return [compress_user(p, tilde_expand, tilde_val) for p in found]
+
+def clear_completer(self, event):
+    "A completer for %clear magic"
+    return 'in out array dhist'.split()

IPython/core/interactiveshell.py

@@ -1840,7 +1840,7 b' class InteractiveShell(SingletonConfigurable, Magic):'
         """
         from IPython.core.completer import IPCompleter
         from IPython.core.completerlib import (module_completer,
-                                               magic_run_completer, cd_completer)
+                magic_run_completer, cd_completer, clear_completer)
 
         self.Completer = IPCompleter(shell=self,
                                      namespace=self.user_ns,
@@ -1860,6 +1860,7 b' class InteractiveShell(SingletonConfigurable, Magic):'
         self.set_hook('complete_command', module_completer, str_key = 'from')
         self.set_hook('complete_command', magic_run_completer, str_key = '%run')
         self.set_hook('complete_command', cd_completer, str_key = '%cd')
+        self.set_hook('complete_command', clear_completer, str_key = '%clear')
 
         # Only configure readline if we truly are using readline.  IPython can
         # do tab-completion over the network, in GUIs, etc, where readline

IPython/core/magic.py

@@ -25,6 +25,7 b' import sys'
 import shutil
 import re
 import time
+import gc
 from StringIO import StringIO
 from getopt import getopt,GetoptError
 from pprint import pformat
@@ -3697,4 +3698,60 b' Defaulting color scheme to \'NoColor\'"""'
             except Exception as e:
                 error(e)
 
+    def magic_clear(self, s):
+        """Clear various data (e.g. stored history data)
+
+        %clear in  - clear input history
+        %clear out - clear output history
+        %clear dhist - clear dir history
+        %clear array - clear only variables that are NumPy arrays
+
+        Examples
+        --------
+        ::
+
+            In [1]: clear in
+            Flushing input history
+
+            In [2]: clear dhist
+            Clearing directory history
+        """
+        ip = self.shell
+        user_ns = self.user_ns  # local lookup, heavily used
+
+        for target in s.split():
+            if target == 'out':
+                print "Flushing output cache (%d entries)" % len(user_ns['_oh'])
+                self.displayhook.flush()
+
+            elif target == 'in':
+                print "Flushing input history"
+                pc = self.displayhook.prompt_count + 1
+                for n in range(1, pc):
+                    key = '_i'+repr(n)
+                    user_ns.pop(key,None)
+                user_ns.update(dict(_i=u'',_ii=u'',_iii=u''))
+                # don't delete these, as %save and %macro depending on the length
+                # of these lists to be preserved
+                self.history_manager.input_hist_parsed[:] = [''] * pc
+                self.history_manager.input_hist_raw[:] = [''] * pc
+
+            elif target == 'array':
+                # Support cleaning up numpy arrays
+                try:
+                    from numpy import ndarray
+                    # This must be done with items and not iteritems because we're
+                    # going to modify the dict in-place.
+                    for x,val in user_ns.items():
+                        if isinstance(val,ndarray):
+                            del user_ns[x]
+                except ImportError:
+                    print "Clear array only works if Numpy is available."
+
+            elif target == 'dhist':
+                print "Clearing directory history"
+                del user_ns['_dh'][:]
+
+            gc.collect()
+
 # end Magic

IPython/core/tests/test_magic.py

@@ -187,7 +187,6 b' def test_macro_run():'
 @dec.skipif_not_numpy
 def test_numpy_clear_array_undec():
     "Test '%clear array' functionality"
-    _ip.magic("load_ext clearcmd")
     _ip.ex('import numpy as np')
     _ip.ex('a = np.empty(2)')
     yield (nt.assert_true, 'a' in _ip.user_ns)
@@ -197,7 +196,6 b' def test_numpy_clear_array_undec():'
 def test_clear():
     "Test '%clear' magic provided by IPython.extensions.clearcmd"
     _ip = get_ipython()
-    _ip.magic("load_ext clearcmd")
     _ip.run_cell("parrot = 'dead'", store_history=True)
     # test '%clear out', make an Out prompt
     _ip.run_cell("parrot", store_history=True)

IPython/quarantine/ipy_jot.py

@@ -116,8 +116,6 b" def jot_obj(self, obj, name, comment=''):"
 
     uname = 'jot/'+name+suffix
 
-    # which one works better?
-    #all = ip.shadowhist.all()
     all = ip.shell.history_manager.input_hist_parsed
 
     # We may actually want to make snapshot of files that are run-ned.