Source code for soma.env

# -*- coding: iso-8859-1 -*-

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'''

- author: Dominique Geffroy
- organization: `NeuroSpin <http://www.neurospin.org>`_ and
  `IFR 49 <http://www.ifr49.org>\\_
- license: `CeCILL version 2 <http://www.cecill.info/licences/Licence_CeCILL_V2-en.html>`_
'''
from __future__ import absolute_import
__docformat__ = 'restructuredtext en'

from soma.singleton import Singleton
import os


class BrainvisaSystemEnv(Singleton):

    """
    This class gets the value of the variables ``BRAINVISA_UNENV_``... if they are defined. These variables store the value of system environment variables that have been modified in brainvisa context.
    The method getVariables returns a map of variable -> value to restore the system value of these environment variables.
    """

    def __singleton_init__(self):
        """
        Define system environment variables that have to be passed to external command to restore environment if it have been modified at brainvisa startup
        """
        super(BrainvisaSystemEnv, self).__singleton_init__()
        # this map will contain {variable : old value} for all varialbes
        # modified at startup
        self.variables = {}
        unenvVars = [
            i for i in os.environ if i.startswith('BRAINVISA_UNENV_')]
        if unenvVars:
            # the old value of these variables was stored in variables
            # BRAINVISA_UNENV_VARIABLE
            for bvSysVar in unenvVars:
                sysVar = bvSysVar[16:]
                self.variables[sysVar] = os.getenv(bvSysVar)

    def getVariables(self):
        '''
        Returns the dictionary of BRAINVISA_UNENV_* variables
        '''
        return self.variables