def generate(env):
    """Add Builders and construction variables for dvips to an Environment."""
    global PSAction
    if PSAction is None:
        PSAction = SCons.Action.Action('$PSCOM', '$PSCOMSTR')

    global DVIPSAction
    if DVIPSAction is None:
        DVIPSAction = SCons.Action.Action(DviPsFunction, strfunction = DviPsStrFunction)

    global PSBuilder
    if PSBuilder is None:
        PSBuilder = SCons.Builder.Builder(action = PSAction,
                                          prefix = '$PSPREFIX',
                                          suffix = '$PSSUFFIX',
                                          src_suffix = '.dvi',
                                          src_builder = 'DVI',
                                          single_source=True)

    env['BUILDERS']['PostScript'] = PSBuilder
    
    env['DVIPS']      = 'dvips'
    env['DVIPSFLAGS'] = SCons.Util.CLVar('')
    # I'm not quite sure I got the directories and filenames right for variant_dir
    # We need to be in the correct directory for the sake of latex \includegraphics eps included files.
    env['PSCOM']      = 'cd ${TARGET.dir} && $DVIPS $DVIPSFLAGS -o ${TARGET.file} ${SOURCE.file}'
    env['PSPREFIX'] = ''
    env['PSSUFFIX'] = '.ps'
Add Builders and construction variables for dvips to an Environment.