jupyter

packages/python/yap_kernel/yap_ipython/utils/syspathcontext.py

@@ -0,0 +1,62 @@
+# encoding: utf-8
+"""
+Context managers for adding things to sys.path temporarily.
+
+Authors:
+
+* Brian Granger
+"""
+
+#-----------------------------------------------------------------------------
+#  Copyright (C) 2008-2011  The yap_ipython Development Team
+#
+#  Distributed under the terms of the BSD License.  The full license is in
+#  the file COPYING, distributed as part of this software.
+#-----------------------------------------------------------------------------
+
+import sys
+
+
+class appended_to_syspath(object):
+    """A context for appending a directory to sys.path for a second."""
+
+    def __init__(self, dir):
+        self.dir = dir
+
+    def __enter__(self):
+        if self.dir not in sys.path:
+            sys.path.append(self.dir)
+            self.added = True
+        else:
+            self.added = False
+
+    def __exit__(self, type, value, traceback):
+        if self.added:
+            try:
+                sys.path.remove(self.dir)
+            except ValueError:
+                pass
+        # Returning False causes any exceptions to be re-raised.
+        return False
+
+class prepended_to_syspath(object):
+    """A context for prepending a directory to sys.path for a second."""
+
+    def __init__(self, dir):
+        self.dir = dir
+
+    def __enter__(self):
+        if self.dir not in sys.path:
+            sys.path.insert(0,self.dir)
+            self.added = True
+        else:
+            self.added = False
+
+    def __exit__(self, type, value, traceback):
+        if self.added:
+            try:
+                sys.path.remove(self.dir)
+            except ValueError:
+                pass
+        # Returning False causes any exceptions to be re-raised.
+        return False