From 0ca84ab9bced68ff8296fb26bc86f3ec44a7b5c3 Mon Sep 17 00:00:00 2001
From: Ben Kurtovic <ben.kurtovic@verizon.net>
Date: Sat, 1 Sep 2012 22:28:30 -0400
Subject: [PATCH] Implement lazy-importing of oauth2, nltk, and bs4.

---
 earwigbot/__init__.py               |  2 --
 earwigbot/lazy.py                   | 11 +++++++++--
 earwigbot/wiki/copyvios/__init__.py | 10 ++++++----
 earwigbot/wiki/copyvios/parsers.py  |  7 +++++--
 earwigbot/wiki/copyvios/search.py   |  5 +++--
 5 files changed, 23 insertions(+), 12 deletions(-)

diff --git a/earwigbot/__init__.py b/earwigbot/__init__.py
index 8dca99f..256837c 100644
--- a/earwigbot/__init__.py
+++ b/earwigbot/__init__.py
@@ -64,5 +64,3 @@ managers = importer.new("earwigbot.managers")
 tasks = importer.new("earwigbot.tasks")
 util = importer.new("earwigbot.util")
 wiki = importer.new("earwigbot.wiki")
-
-del importer
diff --git a/earwigbot/lazy.py b/earwigbot/lazy.py
index 555f039..f9214e0 100644
--- a/earwigbot/lazy.py
+++ b/earwigbot/lazy.py
@@ -21,8 +21,10 @@
 # SOFTWARE.
 
 """
-Implements a hierarchy of importing classes as defined in PEP 302 to load
-modules in a safe yet lazy manner.
+Implements a hierarchy of importing classes as defined in `PEP 302
+<http://www.python.org/dev/peps/pep-0302/>`_ to load modules in a safe yet lazy
+manner, so that they can be referred to by name but are not actually loaded
+until they are used (i.e. their attributes are read or modified).
 """
 
 from imp import acquire_lock, release_lock
@@ -64,6 +66,11 @@ class _LazyModule(type):
 
 
 class LazyImporter(object):
+    """An importer for modules that are loaded lazily.
+
+    This inserts itself into :py:data:`sys.meta_path`, storing a dictionary of
+    :py:class:`_LazyModule`\ s (which is added to with :py:meth:`new`).
+    """
     def __init__(self):
         self._modules = {}
         sys.meta_path.append(self)
diff --git a/earwigbot/wiki/copyvios/__init__.py b/earwigbot/wiki/copyvios/__init__.py
index cd643f3..425d99a 100644
--- a/earwigbot/wiki/copyvios/__init__.py
+++ b/earwigbot/wiki/copyvios/__init__.py
@@ -26,14 +26,14 @@ from StringIO import StringIO
 from time import sleep, time
 from urllib2 import build_opener, URLError
 
-import oauth2 as oauth
-
-from earwigbot import exceptions
+from earwigbot import exceptions, importer
 from earwigbot.wiki.copyvios.markov import MarkovChain, MarkovChainIntersection
 from earwigbot.wiki.copyvios.parsers import ArticleTextParser, HTMLTextParser
 from earwigbot.wiki.copyvios.result import CopyvioCheckResult
 from earwigbot.wiki.copyvios.search import YahooBOSSSearchEngine
 
+oauth = importer.new("oauth2")
+
 __all__ = ["CopyvioMixIn"]
 
 class CopyvioMixIn(object):
@@ -93,7 +93,9 @@ class CopyvioMixIn(object):
         credentials = self._search_config["credentials"]
 
         if engine == "Yahoo! BOSS":
-            if not oauth:
+            try:
+                oauth.__version__  # Force-load the lazy module
+            except (ImportError, AttributeError):
                 e = "The package 'oauth2' could not be imported"
                 raise exceptions.UnsupportedSearchEngineError(e)
             return YahooBOSSSearchEngine(credentials)
diff --git a/earwigbot/wiki/copyvios/parsers.py b/earwigbot/wiki/copyvios/parsers.py
index 798b2a7..4f8e981 100644
--- a/earwigbot/wiki/copyvios/parsers.py
+++ b/earwigbot/wiki/copyvios/parsers.py
@@ -22,9 +22,12 @@
 
 from os import path
 
-import bs4
 import mwparserfromhell
-import nltk
+
+from earwigbot import importer
+
+bs4 = importer.new("bs4")
+nltk = importer.new("nltk")
 
 __all__ = ["BaseTextParser", "ArticleTextParser", "HTMLTextParser"]
 
diff --git a/earwigbot/wiki/copyvios/search.py b/earwigbot/wiki/copyvios/search.py
index 0834885..a9afcfb 100644
--- a/earwigbot/wiki/copyvios/search.py
+++ b/earwigbot/wiki/copyvios/search.py
@@ -23,10 +23,11 @@
 from json import loads
 from urllib import quote_plus, urlencode
 
-import oauth2 as oauth
-
+from earwigbot import importer
 from earwigbot.exceptions import SearchQueryError
 
+oauth = importer.new("oauth2")
+
 __all__ = ["BaseSearchEngine", "YahooBOSSSearchEngine"]
 
 class BaseSearchEngine(object):