# -*- test-case-name: twisted.python.test.test_deprecate -*-
# Copyright (c) Twisted Matrix Laboratories.
# See LICENSE for details.

"""
Deprecation framework for Twisted.

To mark a method or function as being deprecated do this::

from twisted.python.versions import Version
from twisted.python.deprecate import deprecated

@deprecated(Version("Twisted", 8, 0, 0))
def badAPI(self, first, second):
'''
Docstring for badAPI.
'''
...

The newly-decorated badAPI will issue a warning when called. It will also have
a deprecation notice appended to its docstring.

To mark module-level attributes as being deprecated you can use::

badAttribute = "someValue"

...

deprecatedModuleAttribute(
Version("Twisted", 8, 0, 0),
"Use goodAttribute instead.",
"your.full.module.name",
"badAttribute")

The deprecated attributes will issue a warning whenever they are accessed. If
the attributes being deprecated are in the same module as the
L{deprecatedModuleAttribute} call is being made from, the C{__name__} global
can be used as the C{moduleName} parameter.

See also L{Version}.

@type DEPRECATION_WARNING_FORMAT: C{str}
@var DEPRECATION_WARNING_FORMAT: The default deprecation warning string format
to use when one is not provided by the user.
"""

from __future__ import division, absolute_import

__all__ = [
'deprecated',
'getDeprecationWarningString',
'getWarningMethod',
'setWarningMethod',
'deprecatedModuleAttribute',
]


import sys, inspect
from warnings import warn, warn_explicit
from dis import findlinestarts
from functools import wraps

from twisted.python.versions import getVersionString

DEPRECATION_WARNING_FORMAT = '%(fqpn)s was deprecated in %(version)s'

# Notionally, part of twisted.python.reflect, but defining it there causes a
# cyclic dependency between this module and that module. Define it here,
# instead, and let reflect import it to re-expose to the public.
def _fullyQualifiedName(obj):
"""
Return the fully qualified name of a module, class, method or function.
Classes and functions need to be module level ones to be correctly
qualified.

@rtype: C{str}.
"""
try:
name = obj.__qualname__
except AttributeError:
name = obj.__name__

if inspect.isclass(obj) or inspect.isfunction(obj):
moduleName = obj.__module__
return "%s.%s" % (moduleName, name)
elif inspect.ismethod(obj):
try:
cls = obj.im_class
except AttributeError:
# Python 3 eliminates im_class, substitutes __module__ and
# __qualname__ to provide similar information.
return "%s.%s" % (obj.__module__, obj.__qualname__)
else:
className = _fullyQualifiedName(cls)
return "%s.%s" % (className, name)
return name
# Try to keep it looking like something in twisted.python.reflect.
_fullyQualifiedName.__module__ = 'twisted.python.reflect'
_fullyQualifiedName.__name__ = 'fullyQualifiedName'
_fullyQualifiedName.__qualname__ = 'fullyQualifiedName'


def _getReplacementString(replacement):
"""
Surround a replacement for a deprecated API with some polite text exhorting
the user to consider it as an alternative.

@type replacement: C{str} or callable

@return: a string like "please use twisted.python.modules.getModule
instead".
"""
if callable(replacement):
replacement = _fullyQualifiedName(replacement)
return "please use %s instead" % (replacement,)



def _getDeprecationDocstring(version, replacement=None):
"""
Generate an addition to a deprecated object's docstring that explains its
deprecation.

@param version: the version it was deprecated.
@type version: L{Version}

@param replacement: The replacement, if specified.
@type replacement: C{str} or callable

@return: a string like "Deprecated in Twisted 27.2.0; please use
twisted.timestream.tachyon.flux instead."
"""
doc = "Deprecated in %s" % (getVersionString(version),)
if replacement:
doc = "%s; %s" % (doc, _getReplacementString(replacement))
return doc + "."



def _getDeprecationWarningString(fqpn, version, format=None, replacement=None):
"""
Return a string indicating that the Python name was deprecated in the given
version.

@param fqpn: Fully qualified Python name of the thing being deprecated
@type fqpn: C{str}

@param version: Version that C{fqpn} was deprecated in.
@type version: L{twisted.python.versions.Version}

@param format: A user-provided format to interpolate warning values into, or
L{DEPRECATION_WARNING_FORMAT
<twisted.python.deprecate.DEPRECATION_WARNING_FORMAT>} if C{None} is
given.
@type format: C{str}

@param replacement: what should be used in place of C{fqpn}. Either pass in
a string, which will be inserted into the warning message, or a
callable, which will be expanded to its full import path.
@type replacement: C{str} or callable

@return: A textual description of the deprecation
@rtype: C{str}
"""
if format is None:
format = DEPRECATION_WARNING_FORMAT
warningString = format % {
'fqpn': fqpn,
'version': getVersionString(version)}
if replacement:
warningString = "%s; %s" % (
warningString, _getReplacementString(replacement))
return warningString



def getDeprecationWarningString(callableThing, version, format=None,
replacement=None):
"""
Return a string indicating that the callable was deprecated in the given
version.

@type callableThing: C{callable}
@param callableThing: Callable object to be deprecated

@type version: L{twisted.python.versions.Version}
@param version: Version that C{callableThing} was deprecated in

@type format: C{str}
@param format: A user-provided format to interpolate warning values into,
or L{DEPRECATION_WARNING_FORMAT
<twisted.python.deprecate.DEPRECATION_WARNING_FORMAT>} if C{None} is
given

@param callableThing: A callable to be deprecated.

@param version: The L{twisted.python.versions.Version} that the callable
was deprecated in.

@param replacement: what should be used in place of the callable. Either
pass in a string, which will be inserted into the warning message,
or a callable, which will be expanded to its full import path.
@type replacement: C{str} or callable

@return: A string describing the deprecation.
@rtype: C{str}
"""
return _getDeprecationWarningString(
_fullyQualifiedName(callableThing), version, format, replacement)



def _appendToDocstring(thingWithDoc, textToAppend):
"""
Append the given text to the docstring of C{thingWithDoc}.

If C{thingWithDoc} has no docstring, then the text just replaces the
docstring. If it has a single-line docstring then it appends a blank line
and the message text. If it has a multi-line docstring, then in appends a
blank line a the message text, and also does the indentation correctly.
"""
if thingWithDoc.__doc__:
docstringLines = thingWithDoc.__doc__.splitlines()
else:
docstringLines = []

if len(docstringLines) == 0:
docstringLines.append(textToAppend)
elif len(docstringLines) == 1:
docstringLines.extend(['', textToAppend, ''])
else:
spaces = docstringLines.pop()
docstringLines.extend(['',
spaces + textToAppend,
spaces])
thingWithDoc.__doc__ = '\n'.join(docstringLines)



def deprecated(version, replacement=None):
"""
Return a decorator that marks callables as deprecated.

@type version: L{twisted.python.versions.Version}
@param version: The version in which the callable will be marked as
having been deprecated. The decorated function will be annotated
with this version, having it set as its C{deprecatedVersion}
attribute.

@param version: the version that the callable was deprecated in.
@type version: L{twisted.python.versions.Version}

@param replacement: what should be used in place of the callable. Either
pass in a string, which will be inserted into the warning message,
or a callable, which will be expanded to its full import path.
@type replacement: C{str} or callable
"""
def deprecationDecorator(function):
"""
Decorator that marks C{function} as deprecated.
"""
warningString = getDeprecationWarningString(
function, version, None, replacement)

@wraps(function)
def deprecatedFunction(*args, **kwargs):
warn(
warningString,
DeprecationWarning,
stacklevel=2)
return function(*args, **kwargs)

_appendToDocstring(deprecatedFunction,
_getDeprecationDocstring(version, replacement))
deprecatedFunction.deprecatedVersion = version
return deprecatedFunction

return deprecationDecorator



def getWarningMethod():
"""
Return the warning method currently used to record deprecation warnings.
"""
return warn



def setWarningMethod(newMethod):
"""
Set the warning method to use to record deprecation warnings.

The callable should take message, category and stacklevel. The return
value is ignored.
"""
global warn
warn = newMethod



class _InternalState(object):
"""
An L{_InternalState} is a helper object for a L{_ModuleProxy}, so that it
can easily access its own attributes, bypassing its logic for delegating to
another object that it's proxying for.

@ivar proxy: a L{ModuleProxy}
"""
def __init__(self, proxy):
object.__setattr__(self, 'proxy', proxy)


def __getattribute__(self, name):
return object.__getattribute__(object.__getattribute__(self, 'proxy'),
name)


def __setattr__(self, name, value):
return object.__setattr__(object.__getattribute__(self, 'proxy'),
name, value)



class _ModuleProxy(object):
"""
Python module wrapper to hook module-level attribute access.

Access to deprecated attributes first checks
L{_ModuleProxy._deprecatedAttributes}, if the attribute does not appear
there then access falls through to L{_ModuleProxy._module}, the wrapped
module object.

@ivar _module: Module on which to hook attribute access.
@type _module: C{module}

@ivar _deprecatedAttributes: Mapping of attribute names to objects that
retrieve the module attribute's original value.
@type _deprecatedAttributes: C{dict} mapping C{str} to
L{_DeprecatedAttribute}

@ivar _lastWasPath: Heuristic guess as to whether warnings about this
package should be ignored for the next call. If the last attribute
access of this module was a C{getattr} of C{__path__}, we will assume
that it was the import system doing it and we won't emit a warning for
the next access, even if it is to a deprecated attribute. The CPython
import system always tries to access C{__path__}, then the attribute
itself, then the attribute itself again, in both successful and failed
cases.
@type _lastWasPath: C{bool}
"""
def __init__(self, module):
state = _InternalState(self)
state._module = module
state._deprecatedAttributes = {}
state._lastWasPath = False


def __repr__(self):
"""
Get a string containing the type of the module proxy and a
representation of the wrapped module object.
"""
state = _InternalState(self)
return '<%s module=%r>' % (type(self).__name__, state._module)


def __setattr__(self, name, value):
"""
Set an attribute on the wrapped module object.
"""
state = _InternalState(self)
state._lastWasPath = False
setattr(state._module, name, value)


def __getattribute__(self, name):
"""
Get an attribute from the module object, possibly emitting a warning.

If the specified name has been deprecated, then a warning is issued.
(Unless certain obscure conditions are met; see
L{_ModuleProxy._lastWasPath} for more information about what might quash
such a warning.)
"""
state = _InternalState(self)
if state._lastWasPath:
deprecatedAttribute = None
else:
deprecatedAttribute = state._deprecatedAttributes.get(name)

if deprecatedAttribute is not None:
# If we have a _DeprecatedAttribute object from the earlier lookup,
# allow it to issue the warning.
value = deprecatedAttribute.get()
else:
# Otherwise, just retrieve the underlying value directly; it's not
# deprecated, there's no warning to issue.
value = getattr(state._module, name)
if name == '__path__':
state._lastWasPath = True
else:
state._lastWasPath = False
return value



class _DeprecatedAttribute(object):
"""
Wrapper for deprecated attributes.

This is intended to be used by L{_ModuleProxy}. Calling
L{_DeprecatedAttribute.get} will issue a warning and retrieve the
underlying attribute's value.

@type module: C{module}
@ivar module: The original module instance containing this attribute

@type fqpn: C{str}
@ivar fqpn: Fully qualified Python name for the deprecated attribute

@type version: L{twisted.python.versions.Version}
@ivar version: Version that the attribute was deprecated in

@type message: C{str}
@ivar message: Deprecation message
"""
def __init__(self, module, name, version, message):
"""
Initialise a deprecated name wrapper.
"""
self.module = module
self.__name__ = name
self.fqpn = module.__name__ + '.' + name
self.version = version
self.message = message


def get(self):
"""
Get the underlying attribute value and issue a deprecation warning.
"""
# This might fail if the deprecated thing is a module inside a package.
# In that case, don't emit the warning this time. The import system
# will come back again when it's not an AttributeError and we can emit
# the warning then.
result = getattr(self.module, self.__name__)
message = _getDeprecationWarningString(self.fqpn, self.version,
DEPRECATION_WARNING_FORMAT + ': ' + self.message)
warn(message, DeprecationWarning, stacklevel=3)
return result



def _deprecateAttribute(proxy, name, version, message):
"""
Mark a module-level attribute as being deprecated.

@type proxy: L{_ModuleProxy}
@param proxy: The module proxy instance proxying the deprecated attributes

@type name: C{str}
@param name: Attribute name

@type version: L{twisted.python.versions.Version}
@param version: Version that the attribute was deprecated in

@type message: C{str}
@param message: Deprecation message
"""
_module = object.__getattribute__(proxy, '_module')
attr = _DeprecatedAttribute(_module, name, version, message)
# Add a deprecated attribute marker for this module's attribute. When this
# attribute is accessed via _ModuleProxy a warning is emitted.
_deprecatedAttributes = object.__getattribute__(
proxy, '_deprecatedAttributes')
_deprecatedAttributes[name] = attr



def deprecatedModuleAttribute(version, message, moduleName, name):
"""
Declare a module-level attribute as being deprecated.

@type version: L{twisted.python.versions.Version}
@param version: Version that the attribute was deprecated in

@type message: C{str}
@param message: Deprecation message

@type moduleName: C{str}
@param moduleName: Fully-qualified Python name of the module containing
the deprecated attribute; if called from the same module as the
attributes are being deprecated in, using the C{__name__} global can
be helpful

@type name: C{str}
@param name: Attribute name to deprecate
"""
module = sys.modules[moduleName]
if not isinstance(module, _ModuleProxy):
module = _ModuleProxy(module)
sys.modules[moduleName] = module

_deprecateAttribute(module, name, version, message)


def warnAboutFunction(offender, warningString):
"""
Issue a warning string, identifying C{offender} as the responsible code.

This function is used to deprecate some behavior of a function. It differs
from L{warnings.warn} in that it is not limited to deprecating the behavior
of a function currently on the call stack.

@param function: The function that is being deprecated.

@param warningString: The string that should be emitted by this warning.
@type warningString: C{str}

@since: 11.0
"""
# inspect.getmodule() is attractive, but somewhat
# broken in Python < 2.6. See Python bug 4845.
offenderModule = sys.modules[offender.__module__]
filename = inspect.getabsfile(offenderModule)
lineStarts = list(findlinestarts(offender.__code__))
lastLineNo = lineStarts[-1][1]
globals = offender.__globals__

kwargs = dict(
category=DeprecationWarning,
filename=filename,
lineno=lastLineNo,
module=offenderModule.__name__,
registry=globals.setdefault("__warningregistry__", {}),
module_globals=None)

warn_explicit(warningString, **kwargs)