new way of loading extensions, thanks @takluyver

IPython/core/tests/test_magic.py

@@ -187,8 +187,7 b' def test_macro_run():'
 @dec.skipif_not_numpy
 def test_numpy_clear_array_undec():
     "Test '%clear array' functionality"
-    from IPython.extensions import clearcmd
-
+    _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)
@@ -197,8 +196,8 b' def test_numpy_clear_array_undec():'
 
 def test_clear():
     "Test '%clear' magic provided by IPython.extensions.clearcmd"
-    from IPython.extensions import 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/extensions/clearcmd.py

@@ -1,9 +1,7 b''
 # -*- coding: utf-8 -*-
 """ IPython extension: add %clear magic """
 
-from IPython.core import ipapi
 import gc
-ip = ipapi.get()
 
 def clear_f(self,arg):
     """ Clear various data (e.g. stored history data)
@@ -30,7 +28,7 b' def clear_f(self,arg):'
     Clearing directory history
     """
 
-    api = self.get_ipython()
+    ip = self.shell
     user_ns = self.user_ns  # local lookup, heavily used
 
 
@@ -64,7 +62,7 b' def clear_f(self,arg):'
 
         elif target == 'shadow_compress':
             print "Compressing shadow history"
-            api.db.hcompress('shadowhist')
+            ip.db.hcompress('shadowhist')
 
         elif target == 'shadow_nuke':
             print "Erased all keys from shadow history "
@@ -77,7 +75,13 b' def clear_f(self,arg):'
 
     gc.collect()
 
+_loaded = False
+
 # Activate the extension
-ip.define_magic("clear",clear_f)
-from IPython.core.completerlib import quick_completer
-quick_completer('%clear','in out array shadow_nuke shadow_compress dhist')
+def load_ipython_extension(ip):
+    """Load the extension in IPython."""
+    global _loaded
+    if not _loaded:
+        ip.define_magic("clear",clear_f)
+        from IPython.core.completerlib import quick_completer
+        quick_completer('%clear','in out array shadow_nuke shadow_compress dhist')