这是Paul McGuire 的 DocStringInheritor 元类的变体。
- 如果子成员的文档字符串为空,它将继承父成员的文档字符串。
- 如果子类文档字符串为空,它将继承父类文档字符串。
- 它可以从任何基类的 MRO 中的任何类继承文档字符串,就像常规属性继承一样。
- 与类装饰器不同,元类是继承的,因此您只需在某个顶级基类中设置一次元类,文档字符串继承将在整个 OOP 层次结构中发生。
import unittest
import sys
class DocStringInheritor(type):
"""
A variation on
http://groups.google.com/group/comp.lang.python/msg/26f7b4fcb4d66c95
by Paul McGuire
"""
def __new__(meta, name, bases, clsdict):
if not('__doc__' in clsdict and clsdict['__doc__']):
for mro_cls in (mro_cls for base in bases for mro_cls in base.mro()):
doc=mro_cls.__doc__
if doc:
clsdict['__doc__']=doc
break
for attr, attribute in clsdict.items():
if not attribute.__doc__:
for mro_cls in (mro_cls for base in bases for mro_cls in base.mro()
if hasattr(mro_cls, attr)):
doc=getattr(getattr(mro_cls,attr),'__doc__')
if doc:
if isinstance(attribute, property):
clsdict[attr] = property(attribute.fget, attribute.fset,
attribute.fdel, doc)
else:
attribute.__doc__ = doc
break
return type.__new__(meta, name, bases, clsdict)
class Test(unittest.TestCase):
def test_null(self):
class Foo(object):
def frobnicate(self): pass
class Bar(Foo, metaclass=DocStringInheritor):
pass
self.assertEqual(Bar.__doc__, object.__doc__)
self.assertEqual(Bar().__doc__, object.__doc__)
self.assertEqual(Bar.frobnicate.__doc__, None)
def test_inherit_from_parent(self):
class Foo(object):
'Foo'
def frobnicate(self):
'Frobnicate this gonk.'
class Bar(Foo, metaclass=DocStringInheritor):
pass
self.assertEqual(Foo.__doc__, 'Foo')
self.assertEqual(Foo().__doc__, 'Foo')
self.assertEqual(Bar.__doc__, 'Foo')
self.assertEqual(Bar().__doc__, 'Foo')
self.assertEqual(Bar.frobnicate.__doc__, 'Frobnicate this gonk.')
def test_inherit_from_mro(self):
class Foo(object):
'Foo'
def frobnicate(self):
'Frobnicate this gonk.'
class Bar(Foo):
pass
class Baz(Bar, metaclass=DocStringInheritor):
pass
self.assertEqual(Baz.__doc__, 'Foo')
self.assertEqual(Baz().__doc__, 'Foo')
self.assertEqual(Baz.frobnicate.__doc__, 'Frobnicate this gonk.')
def test_inherit_metaclass_(self):
class Foo(object):
'Foo'
def frobnicate(self):
'Frobnicate this gonk.'
class Bar(Foo, metaclass=DocStringInheritor):
pass
class Baz(Bar):
pass
self.assertEqual(Baz.__doc__, 'Foo')
self.assertEqual(Baz().__doc__, 'Foo')
self.assertEqual(Baz.frobnicate.__doc__, 'Frobnicate this gonk.')
def test_property(self):
class Foo(object):
@property
def frobnicate(self):
'Frobnicate this gonk.'
class Bar(Foo, metaclass=DocStringInheritor):
@property
def frobnicate(self): pass
self.assertEqual(Bar.frobnicate.__doc__, 'Frobnicate this gonk.')
if __name__ == '__main__':
sys.argv.insert(1, '--verbose')
unittest.main(argv=sys.argv)