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