Defer import of urllib

IPython/core/extensions.py

@@ -20,8 +20,6 b' Authors:'
 import os
 from shutil import copyfile
 import sys
-from urllib import urlretrieve
-from urlparse import urlparse
 
 from IPython.core.error import UsageError
 from IPython.config.configurable import Configurable
@@ -171,6 +169,8 b' class ExtensionManager(Configurable):'
             src_filename = os.path.basename(url)
             copy = copyfile
         else:
+            from urllib import urlretrieve  # Deferred imports
+            from urlparse import urlparse
             src_filename = urlparse(url).path.split('/')[-1]
             copy = urlretrieve
             

IPython/core/interactiveshell.py

@@ -28,7 +28,6 b' import runpy'
 import sys
 import tempfile
 import types
-import urllib
 from io import open as io_open
 
 from IPython.config.configurable import SingletonConfigurable
@@ -2989,7 +2988,8 b' class InteractiveShell(SingletonConfigurable):'
                 return openpy.read_py_url(utarget, skip_encoding_cookie=skip_encoding_cookie)
         except UnicodeDecodeError:
             if not py_only :
-                response = urllib.urlopen(target)
+                from urllib import urlopen  # Deferred import
+                response = urlopen(target)
                 return response.read().decode('latin1')
             raise ValueError(("'%s' seem to be unreadable.") % utarget)
 

IPython/core/magics/code.py

@@ -19,7 +19,6 b' import json'
 import os
 import re
 import sys
-from urllib2 import urlopen
 
 # Our own packages
 from IPython.core.error import TryNext, StdinNotImplementedError, UsageError
@@ -151,6 +150,7 b' class CodeMagics(Magics):'
           }
         }).encode('utf-8')
 
+        from urllib2 import urlopen  # Deferred import
         response = urlopen("https://api.github.com/gists", post_data)
         response_data = json.loads(response.read().decode('utf-8'))
         return response_data['html_url']

IPython/lib/display.py

@@ -2,8 +2,6 b''
 
 Authors : MinRK, gregcaporaso, dannystaple
 """
-import urllib
-
 from os.path import exists, isfile, splitext, abspath, join, isdir
 from os import walk, sep
 
@@ -41,7 +39,8 b' class YouTubeVideo(object):'
     def _repr_html_(self):
         """return YouTube embed iframe for this video id"""
         if self.params:
-            params = "?" + urllib.urlencode(self.params)
+            from urllib import urlencode  # Deferred import
+            params = "?" + urlencode(self.params)
         else:
             params = ""
         return """

IPython/utils/openpy.py

@@ -9,7 +9,6 b' from __future__ import absolute_import'
 import io
 from io import TextIOWrapper, BytesIO
 import re
-import urllib
 
 cookie_re = re.compile(ur"coding[:=]\s*([-\w.]+)", re.UNICODE)
 cookie_comment_re = re.compile(ur"^\s*#.*coding[:=]\s*([-\w.]+)", re.UNICODE)
@@ -205,7 +204,8 b" def read_py_url(url, errors='replace', skip_encoding_cookie=True):"
     -------
     A unicode string containing the contents of the file.
     """
-    response = urllib.urlopen(url)
+    from urllib import urlopen  # Deferred import for faster start
+    response = urlopen(url)
     buffer = io.BytesIO(response.read())
     return source_to_unicode(buffer, errors, skip_encoding_cookie)