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# encoding: utf-8
"""
Context managers for adding things to sys.path temporarily.
Authors:
* Brian Granger
"""
#-----------------------------------------------------------------------------
# Copyright (C) 2008-2011 The 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.
#-----------------------------------------------------------------------------
#-----------------------------------------------------------------------------
# Imports
#-----------------------------------------------------------------------------
import sys
from IPython.utils.py3compat import cast_bytes_py2
#-----------------------------------------------------------------------------
# Code
#-----------------------------------------------------------------------------
class appended_to_syspath(object):
"""A context for appending a directory to sys.path for a second."""
def __init__(self, dir):
self.dir = cast_bytes_py2(dir, sys.getdefaultencoding())
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 = cast_bytes_py2(dir, sys.getdefaultencoding())
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
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