~drizzle-trunk/drizzle/development

#! /usr/bin/env python

# -*- mode: python; indent-tabs-mode: nil; -*-

# vim:expandtab:shiftwidth=2:tabstop=2:smarttab:

#

# Copyright (C) 2011 Patrick Crews

#

# This program is free software; you can redistribute it and/or modify

# it under the terms of the GNU General Public License as published by

# the Free Software Foundation; either version 2 of the License, or

# (at your option) any later version.

#

# This program is distributed in the hope that it will be useful,

# but WITHOUT ANY WARRANTY; without even the implied warranty of

# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

# GNU General Public License for more details.

#

# You should have received a copy of the GNU General Public License

# along with this program; if not, write to the Free Software

# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

"""environment_management

   code we use to tweak the environment during test execution

"""

# imports

import os

import sys

import copy

class environmentManager():

    """ Handles updating / managing environment stuff """

    def __init__(self, system_manager, variables):

        self.system_manager = system_manager

        self.logging = self.system_manager.logging

        self.env_var_delimiter = ':'

    def join_env_var_values(self, value_list):

        """ Utility to join multiple values into a nice string

            for setting an env var to

        """

        return self.env_var_delimiter.join(value_list)

    def set_env_var(self, var_name, var_value, quiet=0):

        """Set an environment variable.  We really just abstract

           voodoo on os.environ

        """

        if not quiet:

            self.logging.debug("Setting env var: %s" %(var_name))

        try:

            os.environ[var_name]=var_value

        except Exception, e:

            self.logging.error("Issue setting environment variable %s to value %s" %(var_name, var_value))

            self.logging.error("%s" %(e))

            sys.exit(1)

    def update_environment_vars(self, desired_vars, working_environment=None):

        """ We update the environment vars with desired_vars

            The expectation is that you know what you are asking for ; )

            If working_environment is provided, we will update that with

            desired_vars.  We operate directly on os.environ by default

            We return our updated environ dictionary

        """

        if not working_environment:

            working_environment = os.environ

        working_environment.update(desired_vars)

        return working_environment

    def create_working_environment(self, desired_vars):

        """ We return a copy of os.environ updated with desired_vars """

        working_copy = copy.deepcopy(os.environ)

        return self.update_environment_vars( desired_vars

                                    , working_environment = working_copy )

    def append_env_var(self, var_name, append_string, suffix=1, quiet=0):

        """ We add the values in var_values to the environment variable 

            var_name.  Depending on suffix value, we either append or prepend

            we return a string suitable for os.putenv

        """

        new_var_value = ""

        if var_name in os.environ:

            cur_var_value = os.environ[var_name]

            if suffix: # We add new values to end of existing value

                new_var_values = [ cur_var_value, append_string ]

            else:

                new_var_values = [ append_string, cur_var_value ]

            new_var_value = self.env_var_delimiter.join(new_var_values)

        else:

            # No existing variable value

            new_var_value = append_string

        return new_var_value