summaryrefslogtreecommitdiff
path: root/deprecation.py
blob: 5e2f813ab066f3cc1fcc145271e2aa825cee8836 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
# copyright 2003-2012 LOGILAB S.A. (Paris, FRANCE), all rights reserved.
# contact http://www.logilab.fr/ -- mailto:contact@logilab.fr
#
# This file is part of logilab-common.
#
# logilab-common is free software: you can redistribute it and/or modify it under
# the terms of the GNU Lesser General Public License as published by the Free
# Software Foundation, either version 2.1 of the License, or (at your option) any
# later version.
#
# logilab-common 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 Lesser General Public License for more
# details.
#
# You should have received a copy of the GNU Lesser General Public License along
# with logilab-common.  If not, see <http://www.gnu.org/licenses/>.
"""Deprecation utilities."""

__docformat__ = "restructuredtext en"

import sys
from warnings import warn

class class_deprecated(type):
    """metaclass to print a warning on instantiation of a deprecated class"""

    def __call__(cls, *args, **kwargs):
        msg = getattr(cls, "__deprecation_warning__",
                      "%(cls)s is deprecated") % {'cls': cls.__name__}
        warn(msg, DeprecationWarning, stacklevel=2)
        return type.__call__(cls, *args, **kwargs)


def class_renamed(old_name, new_class, message=None):
    """automatically creates a class which fires a DeprecationWarning
    when instantiated.

    >>> Set = class_renamed('Set', set, 'Set is now replaced by set')
    >>> s = Set()
    sample.py:57: DeprecationWarning: Set is now replaced by set
      s = Set()
    >>>
    """
    clsdict = {}
    if message is None:
        message = '%s is deprecated, use %s' % (old_name, new_class.__name__)
    clsdict['__deprecation_warning__'] = message
    try:
        # new-style class
        return class_deprecated(old_name, (new_class,), clsdict)
    except (NameError, TypeError):
        # old-style class
        class DeprecatedClass(new_class):
            """FIXME: There might be a better way to handle old/new-style class
            """
            def __init__(self, *args, **kwargs):
                warn(message, DeprecationWarning, stacklevel=2)
                new_class.__init__(self, *args, **kwargs)
        return DeprecatedClass


def class_moved(new_class, old_name=None, message=None):
    """nice wrapper around class_renamed when a class has been moved into
    another module
    """
    if old_name is None:
        old_name = new_class.__name__
    if message is None:
        message = 'class %s is now available as %s.%s' % (
            old_name, new_class.__module__, new_class.__name__)
    return class_renamed(old_name, new_class, message)

def deprecated(reason=None, stacklevel=2, name=None, doc=None):
    """Decorator that raises a DeprecationWarning to print a message
    when the decorated function is called.
    """
    def deprecated_decorator(func):
        message = reason or 'The function "%s" is deprecated'
        if '%s' in message:
            message = message % func.func_name
        def wrapped(*args, **kwargs):
            warn(message, DeprecationWarning, stacklevel=stacklevel)
            return func(*args, **kwargs)
        try:
            wrapped.__name__ = name or func.__name__
        except TypeError: # readonly attribute in 2.3
            pass
        wrapped.__doc__ = doc or func.__doc__
        return wrapped
    return deprecated_decorator

def moved(modpath, objname):
    """use to tell that a callable has been moved to a new module.

    It returns a callable wrapper, so that when its called a warning is printed
    telling where the object can be found, import is done (and not before) and
    the actual object is called.

    NOTE: the usage is somewhat limited on classes since it will fail if the
    wrapper is use in a class ancestors list, use the `class_moved` function
    instead (which has no lazy import feature though).
    """
    def callnew(*args, **kwargs):
        from logilab.common.modutils import load_module_from_name
        message = "object %s has been moved to module %s" % (objname, modpath)
        warn(message, DeprecationWarning, stacklevel=2)
        m = load_module_from_name(modpath)
        return getattr(m, objname)(*args, **kwargs)
    return callnew



class DeprecationWrapper(object):
    """proxy to print a warning on access to any attribute of the wrapped object
    """
    def __init__(self, proxied, msg=None):
        self._proxied = proxied
        self._msg = msg

    def __getattr__(self, attr):
        warn(self._msg, DeprecationWarning, stacklevel=2)
        return getattr(self._proxied, attr)

    def __setattr__(self, attr, value):
        if attr in ('_proxied', '_msg'):
            self.__dict__[attr] = value
        else:
            warn(self._msg, DeprecationWarning, stacklevel=2)
            setattr(self._proxied, attr, value)