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avoid executing code in utils.localinterfaces at import time...
avoid executing code in utils.localinterfaces at import time moves away from global constants to utility functions. The code is still only executed once, but instead of at import time, it is executed at first request.

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syspathcontext.py
69 lines | 2.0 KiB | text/x-python | PythonLexer
# 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
#-----------------------------------------------------------------------------
# Code
#-----------------------------------------------------------------------------
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