Merge pull request ipython#1419 from takluyver/install-ext

Add %install_ext magic function

and associated extension-loading tests

IPython/core/extensions.py

@@ -19,6 +19,8 @@
 
 import os
 import sys
+from urllib import urlretrieve
+from urlparse import urlparse
 
 from IPython.config.configurable import Configurable
 from IPython.utils.traitlets import Instance
@@ -123,3 +125,22 @@ def _call_load_ipython_extension(self, mod):
     def _call_unload_ipython_extension(self, mod):
         if hasattr(mod, 'unload_ipython_extension'):
             return mod.unload_ipython_extension(self.shell)
+
+    def install_extension(self, url, filename=None):
+        """Download and install an IPython extension. 
+        
+        If filename is given, the file will be so named (inside the extension
+        directory). Otherwise, the name from the URL will be used. The file must
+        have a .py or .zip extension; otherwise, a ValueError will be raised.
+        """
+        # Ensure the extension directory exists
+        if not os.path.isdir(self.ipython_extension_dir):
+            os.makedirs(self.ipython_extension_dir, mode = 0777)
+
+        if filename is None:
+            filename = urlparse(url).path.split('/')[-1]
+        if os.path.splitext(filename)[1] not in ('.py', '.zip'):
+            raise ValueError("The file must have a .py or .zip extension", filename)
+
+        filename = os.path.join(self.ipython_extension_dir, filename)
+        return urlretrieve(url, filename)

IPython/core/magic.py

@@ -3457,6 +3457,31 @@ def magic_gui(self, parameter_s=''):
             # print simple error message, rather than traceback if we can't
             # hook up the GUI
             error(str(e))
+
+    def magic_install_ext(self, parameter_s):
+        """Download and install an extension from a URL, e.g.::
+        
+            %install_ext https://bitbucket.org/birkenfeld/ipython-physics/raw/d1310a2ab15d/physics.py
+        
+        The URL should point to an importable Python module - either a .py file
+        or a .zip file.
+        
+        Parameters:
+        
+          -n filename : Specify a name for the file, rather than taking it from
+                        the URL.
+        """
+        opts, args = self.parse_options(parameter_s, 'n:')
+        try:
+            filename, headers = self.extension_manager.install_extension(args, opts.get('n'))
+        except ValueError as e:
+            print e
+            return
+
+        filename = os.path.basename(filename)
+        print "Installed %s. To use it, type:" % filename
+        print "  %%load_ext %s" % os.path.splitext(filename)[0]
+
 
     def magic_load_ext(self, module_str):
         """Load an IPython extension by its module name."""

IPython/core/tests/daft_extension.py

@@ -0,0 +1,12 @@
+# -*- coding: utf-8 -*-
+"""
+Useless IPython extension to test installing and loading extensions.
+"""
+some_vars = {'arq': 185}
+
+def load_ipython_extension(ip):
+    # set up simplified quantity input
+    ip.push(some_vars)
+
+def unload_ipython_extension(ip):
+    ip.drop_by_id(some_vars)

IPython/core/tests/test_magic.py

@@ -15,6 +15,7 @@
 from IPython.testing import decorators as dec
 from IPython.testing import tools as tt
 from IPython.utils import py3compat
+from IPython.utils.tempdir import TemporaryDirectory
 
 #-----------------------------------------------------------------------------
 # Test functions begin
@@ -394,3 +395,20 @@ def test_prun_quotes():
     "Test that prun does not clobber string escapes (GH #1302)"
     _ip.magic("prun -q x = '\t'")
     nt.assert_equal(_ip.user_ns['x'], '\t')
+
+def test_extension():
+    tmpdir = TemporaryDirectory()
+    orig_ipython_dir = _ip.ipython_dir
+    try:
+        _ip.ipython_dir = tmpdir.name
+        nt.assert_raises(ImportError, _ip.magic, "load_ext daft_extension")
+        url = os.path.join(os.path.dirname(__file__), "daft_extension.py")
+        _ip.magic("install_ext %s" % url)
+        _ip.user_ns.pop('arq', None)
+        _ip.magic("load_ext daft_extension")
+        tt.assert_equal(_ip.user_ns['arq'], 185)
+        _ip.magic("unload_ext daft_extension")
+        assert 'arq' not in _ip.user_ns
+    finally:
+        _ip.ipython_dir = orig_ipython_dir
+

docs/source/whatsnew/development.txt

@@ -4,3 +4,15 @@
 
 This document describes in-flight development work.
 
+Redesigned IPython notebook user interface
+------------------------------------------
+
+.. add details
+
+Other new features
+------------------
+
+* **%install_ext**: A new magic function to install an IPython extension from
+  a URL. E.g. ``%install_ext https://bitbucket.org/birkenfeld/ipython-physics/raw/d1310a2ab15d/physics.py``.
+
+