~bzr-pqm/bzr/bzr.dev

# 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__ = ['deprecated_function',

           'deprecated_method',

           'DEPRECATED_PARAMETER',

           'deprecated_passed',

           'warn', 'set_warning_method', 'zero_seven',

           'zero_eight',

           ]

from warnings import warn

DEPRECATED_PARAMETER = "A deprecated parameter marker."

zero_seven = "%s was deprecated in version 0.7."

zero_eight = "%s was deprecated in version 0.8."

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

# TODO - maybe this would be easier to use as one 'smart' method that

# guess if it is a method or a class or an attribute ? If so, we can

# add that on top of the primitives, once we have all three written

# - RBC 20050105

def deprecated_function(deprecation_version):

    """Decorate a function so that use of it will trigger a warning."""

    def function_decorator(callable):

        """This is the function python calls to perform the decoration."""

        def decorated_function(*args, **kwargs):

            """This is the decorated function."""

            symbol = "%s.%s" % (callable.__module__, 

                                callable.__name__

                                )

            warn(deprecation_version % symbol, DeprecationWarning, stacklevel=2)

            return callable(*args, **kwargs)

        _populate_decorated(callable, deprecation_version, "function",

                            decorated_function)

        return decorated_function

    return function_decorator

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, stacklevel=2)

            return callable(self, *args, **kwargs)

        _populate_decorated(callable, deprecation_version, "method",

                            decorated_method)

        return decorated_method

    return method_decorator

def deprecated_passed(parameter_value):

    """Return True if parameter_value was used."""

    # FIXME: it might be nice to have a parameter deprecation decorator. 

    # it would need to handle positional and *args and **kwargs parameters,

    # which means some mechanism to describe how the parameter was being

    # passed before deprecation, and some way to deprecate parameters that

    # were not at the end of the arg list. Thats needed for __init__ where

    # we cannot just forward to a new method name.I.e. in the following

    # examples we would want to have callers that pass any value to 'bad' be

    # given a warning - because we have applied:

    # @deprecated_parameter('bad', zero_seven)

    #

    # def __init__(self, bad=None)

    # def __init__(self, bad, other)

    # def __init__(self, **kwargs)

    # RBC 20060116

    return not parameter_value is DEPRECATED_PARAMETER

def _decorate_docstring(callable, deprecation_version, label,

                        decorated_callable):

    docstring_lines = callable.__doc__.split('\n')

    if len(docstring_lines) == 0:

        decorated_callable.__doc__ = deprecation_version % ("This " + label)

    elif len(docstring_lines) == 1:

        decorated_callable.__doc__ = (callable.__doc__ 

                                    + "\n"

                                    + "\n"

                                    + deprecation_version % ("This " + label)

                                    + "\n")

    else:

        spaces = len(docstring_lines[-1])

        new_doc = callable.__doc__

        new_doc += "\n" + " " * spaces

        new_doc += deprecation_version % ("This " + label)

        new_doc += "\n" + " " * spaces

        decorated_callable.__doc__ = new_doc

def _populate_decorated(callable, deprecation_version, label,

                        decorated_callable):

    """Populate attributes like __name__ and __doc__ on the decorated callable.

    """

    _decorate_docstring(callable, deprecation_version, label,

                        decorated_callable)

    decorated_callable.__module__ = callable.__module__

    decorated_callable.__name__ = callable.__name__