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simplify deprecation code (@dangra’s idea)
This commit is contained in:
Mikhail Korobov
parent
39458b7843
commit
1e96063ffa
@ -7,7 +7,7 @@ from scrapy import log
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from scrapy.http import Request
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from scrapy.utils.trackref import object_ref
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from scrapy.utils.url import url_is_from_spider
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from scrapy.utils.deprecate import deprecated_base_class
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from scrapy.utils.deprecate import create_deprecated_class
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class Spider(object_ref):
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@ -65,8 +65,7 @@ class Spider(object_ref):
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__repr__ = __str__
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class BaseSpider(Spider):
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__metaclass__ = deprecated_base_class(Spider, "scrapy.spider.BaseSpider was deprecated. Please inherit from scrapy.spider.Spider.")
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BaseSpider = create_deprecated_class('BaseSpider', Spider)
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class ObsoleteClass(object):
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@ -3,7 +3,7 @@ from __future__ import absolute_import
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import inspect
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import unittest
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import warnings
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from scrapy.utils.deprecate import deprecated_base_class
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from scrapy.utils.deprecate import create_deprecated_class
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class MyWarning(UserWarning):
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pass
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@ -19,17 +19,13 @@ class WarnWhenSubclassedTest(unittest.TestCase):
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def test_no_warning_on_definition(self):
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with warnings.catch_warnings(record=True) as w:
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class Deprecated(NewName):
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__metaclass__ = deprecated_base_class(NewName, "message")
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Deprecated = create_deprecated_class('Deprecated', NewName)
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self.assertEqual(w, [])
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def test_warning_on_subclassing(self):
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with warnings.catch_warnings(record=True) as w:
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class Deprecated(NewName):
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__metaclass__ = deprecated_base_class(NewName, "message", MyWarning)
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Deprecated = create_deprecated_class('Deprecated', NewName, MyWarning)
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class UserClass(Deprecated):
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pass
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@ -37,28 +33,28 @@ class WarnWhenSubclassedTest(unittest.TestCase):
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self.assertEqual(len(w), 1)
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msg = w[0]
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assert issubclass(msg.category, MyWarning)
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self.assertEqual(str(msg.message), "message")
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self.assertEqual(
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str(msg.message),
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"Base class scrapy.tests.test_utils_deprecate.Deprecated of "
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"scrapy.tests.test_utils_deprecate.UserClass was deprecated. "
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"Please inherit from scrapy.tests.test_utils_deprecate.NewName."
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)
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self.assertEqual(msg.lineno, inspect.getsourcelines(UserClass)[1])
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def test_warning_auto_message(self):
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with warnings.catch_warnings(record=True) as w:
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class Deprecated(NewName):
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__metaclass__ = deprecated_base_class(NewName)
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Deprecated = create_deprecated_class('Deprecated', NewName)
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class UserClass2(Deprecated):
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pass
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msg = str(w[0].message)
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self.assertIn("scrapy.tests.test_utils_deprecate.NewName", msg)
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# this doesn't work:
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# self.assertIn("scrapy.tests.test_utils_deprecate.Deprecated", msg)
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self.assertIn("scrapy.tests.test_utils_deprecate.Deprecated", msg)
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def test_issubclass(self):
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with warnings.catch_warnings(record=True):
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class DeprecatedName(NewName):
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__metaclass__ = deprecated_base_class(NewName, "message", MyWarning)
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DeprecatedName = create_deprecated_class('DeprecatedName', NewName)
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class UpdatedUserClass1(NewName):
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pass
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@ -88,9 +84,7 @@ class WarnWhenSubclassedTest(unittest.TestCase):
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def test_isinstance(self):
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with warnings.catch_warnings(record=True):
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class DeprecatedName(NewName):
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__metaclass__ = deprecated_base_class(NewName, "message", MyWarning)
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DeprecatedName = create_deprecated_class('DeprecatedName', NewName)
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class UpdatedUserClass2(NewName):
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pass
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@ -114,14 +108,3 @@ class WarnWhenSubclassedTest(unittest.TestCase):
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assert isinstance(OutdatedUserClass2(), DeprecatedName)
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assert not isinstance(UnrelatedClass(), DeprecatedName)
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assert not isinstance(OldStyleClass(), DeprecatedName)
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def test_invalid_usage(self):
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class SomeClass(object):
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pass
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def define_invalid():
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class DeprecatedName(NewName):
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__metaclass__ = deprecated_base_class(SomeClass)
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self.assertRaises(ValueError, define_invalid)
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@ -4,6 +4,7 @@ import warnings
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import inspect
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from scrapy.exceptions import ScrapyDeprecationWarning
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def attribute(obj, oldattr, newattr, version='0.12'):
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cname = obj.__class__.__name__
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warnings.warn("%s.%s attribute is deprecated and will be no longer supported "
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@ -11,15 +12,12 @@ def attribute(obj, oldattr, newattr, version='0.12'):
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(cname, oldattr, version, cname, newattr), ScrapyDeprecationWarning, stacklevel=3)
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def deprecated_base_class(new_class, message=None, category=ScrapyDeprecationWarning):
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def create_deprecated_class(name, new_class, warn_category=ScrapyDeprecationWarning, message=None):
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"""
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Return a metaclass that causes classes to issue a warning when
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they are subclassed.
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Return a "deprecated" class that causes its subclasses to issue a warning.
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Subclasses of ``new_class`` are considered subclasses of this class.
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In addition to that, subclasses of ``new_class`` are considered subclasses
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of a class this metaclass is applied to.
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It can be used to rename a base class of some user classes, e.g. if we
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It can be used to rename a base class in a library. For example, if we
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have
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class OldName(SomeClass):
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@ -30,30 +28,26 @@ def deprecated_base_class(new_class, message=None, category=ScrapyDeprecationWar
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class NewName(SomeClass):
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# ...
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class OldName(NewName):
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__metaclass__ = deprecated_base_class(NewName, "OldName is deprecated. Please inherit from NewName.")
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OldName = create_deprecated_class('OldName', NewName)
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Then, if user class inherits from OldName, warning is issued. Also, if
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some code uses ``issubclass(sub, OldName)`` or ``isinstance(sub(), OldName)``
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checks they'll still return True if sub is a subclass of NewName instead of
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OldName.
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"""
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class Metaclass(type):
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deprecated = {}
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class DeprecatedClass(type):
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def __init__(cls, name, bases, clsdict):
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if not issubclass(cls, new_class):
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raise ValueError("first parameter of `warn_when_subclassed` must be a superclass of %s" % cls)
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warn_message = message
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if warn_message is None:
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# XXX: how to get a name of deprecated base class?
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cls_name = cls.__module__ + '.' + name
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new_name = new_class.__module__ + '.' + new_class.__name__
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warn_message = "Base class of %s was deprecated. Please inherit from %s." % (cls_name, new_name)
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if len(cls.mro()) > len(new_class.mro()) + 1:
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warnings.warn(warn_message, category, stacklevel=2)
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super(Metaclass, cls).__init__(name, bases, clsdict)
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if 'cls' in deprecated:
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if message is not None:
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msg = message
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else:
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msg = "Base class {0} of {1} was deprecated. Please inherit from {2}."\
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.format(_clspath(deprecated['cls']), _clspath(cls), _clspath(new_class))
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warnings.warn(msg, warn_category, stacklevel=2)
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super(DeprecatedClass, cls).__init__(name, bases, clsdict)
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# see http://www.python.org/dev/peps/pep-3119/#overloading-isinstance-and-issubclass
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# and http://docs.python.org/2/reference/datamodel.html#customizing-instance-and-subclass-checks
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@ -70,5 +64,16 @@ def deprecated_base_class(new_class, message=None, category=ScrapyDeprecationWar
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candidates = {cls, new_class}
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return any(c in candidates for c in mro)
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return Metaclass
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deprecated_cls = DeprecatedClass(name, (new_class,), {})
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deprecated['cls'] = deprecated_cls
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frm = inspect.stack()[1]
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parent_module = inspect.getmodule(frm[0])
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if parent_module is not None:
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deprecated_cls.__module__ = parent_module.__name__
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return deprecated_cls
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def _clspath(cls):
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return '{}.{}'.format(cls.__module__, cls.__name__)
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