# Copyright (C) 2006 by Canonical Ltd
#   Authors: Robert Collins <robert.collins@canonical.com>
#
# 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

"""Symbol versioning

The methods here allow for api symbol versioning.
"""

__all__ = ['warn', 'set_warning_method', 'zero_seven']

from warnings import warn


zero_seven = "%s was deprecated in version 0.7"


def set_warning_method(method):
    """Set the warning method to be used by this module.

    It should take a message and a warning category as warnings.warn does.
    """
    global warn
    warn = method


def deprecated_method(deprecation_version):
    """Decorate a method so that use of it will trigger a warning.
    
    To deprecate an entire class, decorate __init__.
    """

    def method_decorator(callable):
        """This is the function python calls to perform the decoration."""
        
        def decorated_method(self, *args, **kwargs):
            """This is the decorated method."""
            symbol = "%s.%s.%s" % (self.__class__.__module__, 
                                   self.__class__.__name__,
                                   callable.__name__
                                   )
            warn(deprecation_version % symbol, DeprecationWarning)
            return callable(self, *args, **kwargs)
        return decorated_method
    return method_decorator