From 44b77cdb857b95d1f40b0a5a1329830a8e03f630 Mon Sep 17 00:00:00 2001
From: Kovid Goyal <kovid@kovidgoyal.net>
Date: Fri, 15 Aug 2014 14:08:46 +0530
Subject: [PATCH] Prevent import of PyQt4 with an ImportError

---
 src/calibre/startup.py | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/src/calibre/startup.py b/src/calibre/startup.py
index 379475fb97..0f0e769261 100644
--- a/src/calibre/startup.py
+++ b/src/calibre/startup.py
@@ -24,6 +24,18 @@ winutil = winutilerror = None
 if not _run_once:
     _run_once = True
 
+    # Prevent PyQt4 from being loaded
+    class PyQt4Ban(object):
+
+        def find_module(self, fullname, path=None):
+            if fullname.startswith('PyQt4'):
+                return self
+
+        def load_module(self, fullname):
+            raise ImportError('Importing PyQt4 is not allowed as calibre uses PyQt5')
+
+    sys.meta_path.insert(0, PyQt4Ban())
+
     #
     # Platform specific modules
     if iswindows: