Merge pull request #1073 from takluyver/storemagic-plugin

* %store is now a plugin
* adds a 'default_extensions' list for extensions that should always be loaded.

IPython/core/shellapp.py

@@ -131,6 +131,9 b' class InteractiveShellApp(Configurable):'
             # add to self.extensions
             self.extensions.append(new)
 
+    # Extensions that are always loaded (not configurable)
+    default_extensions = List(Unicode, [u'storemagic'], config=False)
+
     exec_files = List(Unicode, config=True,
         help="""List of files to run at IPython startup."""
     )
@@ -158,11 +161,9 b' class InteractiveShellApp(Configurable):'
         This uses the :meth:`ExtensionManager.load_extensions` to load all
         the extensions listed in ``self.extensions``.
         """
-        if not self.extensions:
-            return
         try:
             self.log.debug("Loading IPython extensions...")
-            extensions = self.extensions
+            extensions = self.default_extensions + self.extensions
             for ext in extensions:
                 try:
                     self.log.info("Loading IPython extension: %s" % ext)

IPython/extensions/storemagic.py

@@ -2,22 +2,20 b''
 """
 %store magic for lightweight persistence.
 
-Stores variables, aliases and macros in IPython's database. Stored values will
-be automatically restored whenever the extension is loaded.
+Stores variables, aliases and macros in IPython's database.
 
-To enable this functionality, list it in your default profile
-`ipython_config.py` file::
+To automatically restore stored variables at startup, add this to your
+:file:`ipython_config.py` file::
 
-  c.InteractiveShellApp.extensions = ['storemagic']
-
-Or to use it temporarily, run this in your IPython session::
-
-  %load_ext storemagic
+  c.StoreMagic.autorestore = True
 
 """
 
 from IPython.core.error import TryNext, UsageError
+from IPython.core.plugin import Plugin
+from IPython.testing.skipdoctest import skip_doctest
 from IPython.utils import pickleshare
+from IPython.utils.traitlets import Bool, Instance
 
 import inspect,pickle,os,sys,textwrap
 from IPython.core.fakemodule import FakeModule
@@ -53,6 +51,7 b' def restore_data(ip):'
     restore_aliases(ip)
     restore_dhist(ip)
 
+@skip_doctest
 def magic_store(self, parameter_s=''):
     """Lightweight persistence for python variables.
 
@@ -183,6 +182,24 b" def magic_store(self, parameter_s=''):"
             self.db[ 'autorestore/' + args[0] ] = obj
             print "Stored '%s' (%s)" % (args[0], obj.__class__.__name__)
 
+
+class StoreMagic(Plugin):
+    shell = Instance('IPython.core.interactiveshell.InteractiveShellABC')
+    autorestore = Bool(False, config=True)
+    
+    def __init__(self, shell, config):
+        super(StoreMagic, self).__init__(shell=shell, config=config)
+        shell.define_magic('store', magic_store)
+        
+        if self.autorestore:
+            restore_data(shell)
+
+_loaded = False
+
 def load_ipython_extension(ip):
-    ip.define_magic('store', magic_store)
-    restore_data(ip)
+    """Load the extension in IPython."""
+    global _loaded
+    if not _loaded:
+        plugin = StoreMagic(shell=ip, config=ip.config)
+        ip.plugin_manager.register_plugin('storemagic', plugin)
+        _loaded = True

docs/source/whatsnew/development.txt

@@ -62,8 +62,9 b' New features'
   Terminal frontend by default (:ghpull:`838`).
 
 * **%store**: The ``%store`` magic from earlier versions has been updated and
-  placed in an extension, :ref:`extensions_storemagic`. Add 'storemagic' to ``c.InteractiveShellApp.extensions``
-  in ipython_config.py to enable it (:ghpull:`1029`).
+  re-enabled (:ref:`extensions_storemagic`; :ghpull:`1029`). To autorestore
+  stored variables on startup, specify ``c.StoreMagic.autorestore = True`` in
+  :file:`ipython_config.py`.