[Zodb-checkins] CVS: Zope/lib/python/Persistence/tests - test_ExtensionClass.py:1.1.2.1

Jim Fulton cvs-admin at zope.org
Mon Nov 3 11:20:01 EST 2003


Update of /cvs-repository/Zope/lib/python/Persistence/tests
In directory cvs.zope.org:/tmp/cvs-serv19496/lib/python/Persistence/tests

Added Files:
      Tag: zodb33-devel-branch
	test_ExtensionClass.py 
Log Message:
Added extension to provide a getattr slot that blends the semantics of
persistent.Persistent and ExtensionClass.Base.


=== Added File Zope/lib/python/Persistence/tests/test_ExtensionClass.py ===
##############################################################################
#
# Copyright (c) 2003 Zope Corporation and Contributors.
# All Rights Reserved.
#
# This software is subject to the provisions of the Zope Public License,
# Version 2.0 (ZPL).  A copy of the ZPL should accompany this distribution.
# THIS SOFTWARE IS PROVIDED "AS IS" AND ANY AND ALL EXPRESS OR IMPLIED
# WARRANTIES ARE DISCLAIMED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
# WARRANTIES OF TITLE, MERCHANTABILITY, AGAINST INFRINGEMENT, AND FITNESS
# FOR A PARTICULAR PURPOSE.
#
##############################################################################
"""Test ExtensionClass support in Persistence.Persistent

>>> from ExtensionClass import Base

- Support for a class initialiser:

  >>> class C(Persistent):
  ...   def __class_init__(self):
  ...      print 'class init called'
  ...      print self.__name__
  ...   def bar(self):
  ...      return 'bar called'
  class init called
  C
  >>> c = C()
  >>> int(c.__class__ is C)
  1
  >>> int(c.__class__ is type(c))
  1

- Provide an inheritedAttribute method for looking up attributes in
  base classes:

  >>> class C2(C):
  ...   def bar(*a):
  ...      return C2.inheritedAttribute('bar')(*a), 42
  class init called
  C2
  >>> o = C2()
  >>> o.bar()
  ('bar called', 42)

  This is for compatability with old code. New code should use super
  instead.   

The base class, Base, exists mainly to support the __of__ protocol.
The __of__ protocol is similar to __get__ except that __of__ is called
when an implementor is retrieved from an instance as well as from a
class:

>>> class O(Base):
..   def __of__(*a):
..      return a
 
>>> o1 = O()
>>> o2 = O()
>>> C.o1 = o1
>>> c.o2 = o2
>>> c.o1 == (o1, c)
1
>>> C.o1 == o1
1
>>> int(c.o2 == (o2, c))
1

We accomplish this by making a class that implements __of__ a
descriptor and treating all descriptor ExtensionClasses this way. That
is, if an extension class is a descriptor, it's __get__ method will be
called even when it is retrieved from an instance.

>>> class O(Base):
..   def __get__(*a):
..      return a
.. 
>>> o1 = O()
>>> o2 = O()
>>> C.o1 = o1
>>> c.o2 = o2
>>> int(c.o1 == (o1, c, type(c)))
1
>>> int(C.o1 == (o1, None, type(c)))
1
>>> int(c.o2 == (o2, c, type(c)))
1

$Id: test_ExtensionClass.py,v 1.1.2.1 2003/11/03 16:20:00 jim Exp $
"""

from Persistence import Persistent
import pickle


def test_mixing():
    """Test working with a classic class

    >>> class Classic: 
    ...   def x(self): 
    ...     return 42

    >>> class O(Persistent):
    ...   def __of__(*a):
    ...      return a

    >>> class O2(Classic, O):
    ...   def __of__(*a):
    ...      return (O2.inheritedAttribute('__of__')(*a), 
    ...              O2.inheritedAttribute('x')(a[0]))

    >>> class C(Persistent):
    ...   def __class_init__(self):
    ...      print 'class init called'
    ...      print self.__name__
    ...   def bar(self):
    ...      return 'bar called'
    class init called
    C

    >>> c = C()
    >>> o2 = O2()
    >>> c.o2 = o2
    >>> int(c.o2 == ((o2, c), 42))
    1

    Test working with a new style

    >>> class Modern(object): 
    ...   def x(self): 
    ...     return 42

    >>> class O2(Modern, O):
    ...   def __of__(*a):
    ...      return (O2.inheritedAttribute('__of__')(*a), 
    ...              O2.inheritedAttribute('x')(a[0]))

    >>> o2 = O2()
    >>> c.o2 = o2
    >>> int(c.o2 == ((o2, c), 42))
    1

    """

def test_class_creation_under_stress():
    """
    >>> for i in range(100): 
    ...   class B(Persistent):
    ...     print i,
    ...     if i and i%20 == 0:
    ...         print
    0 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

    >>> import gc
    >>> x = gc.collect()

    """

def proper_error_on_deleattr():
    """
    Florent Guillaume wrote:

    ...

    Excellent.
    Will it also fix this particularity of ExtensionClass:
    
    
    >>> class A(Persistent):
    ...   def foo(self):
    ...     self.gee
    ...   def bar(self):
    ...     del self.gee
    
    >>> a=A()
    >>> a.foo()
    Traceback (most recent call last):
    ...
    AttributeError: gee
    
    >>> a.bar()
    Traceback (most recent call last):
    ...
    AttributeError: 'A' object has no attribute 'gee'
    
    I.e., the fact that KeyError is raised whereas a normal class would
    raise AttributeError.
    """

def test__basicnew__():
    """
    >>> x = Simple.__basicnew__()
    >>> x.__dict__
    {}
    """

def print_dict(d):
    d = d.items()
    d.sort()
    print '{%s}' % (', '.join(
        [('%r: %r' % (k, v)) for (k, v) in d]
        ))

def cmpattrs(self, other, *attrs):
    for attr in attrs:
        if attr[:3] in ('_v_', '_p_'):
            continue
        c = cmp(getattr(self, attr, None), getattr(other, attr, None))
        if c:
            return c
    return 0

class Simple(Persistent):
    def __init__(self, name, **kw):
        self.__name__ = name
        self.__dict__.update(kw)
        self._v_favorite_color = 'blue'
        self._p_foo = 'bar'

    def __cmp__(self, other):
        return cmpattrs(self, other, '__class__', *(self.__dict__.keys()))

def test_basic_pickling():
    """
    >>> x = Simple('x', aaa=1, bbb='foo')

    >>> x.__getnewargs__()
    ()

    >>> print_dict(x.__getstate__())
    {'__name__': 'x', 'aaa': 1, 'bbb': 'foo'}
    
    >>> f, (c,), state = x.__reduce__()
    >>> f.__name__
    '__newobj__'
    >>> f.__module__
    'copy_reg'
    >>> c.__name__
    'Simple'
    
    >>> print_dict(state)
    {'__name__': 'x', 'aaa': 1, 'bbb': 'foo'}
    
    >>> pickle.loads(pickle.dumps(x)) == x
    1
    >>> pickle.loads(pickle.dumps(x, 0)) == x
    1
    >>> pickle.loads(pickle.dumps(x, 1)) == x
    1
    >>> pickle.loads(pickle.dumps(x, 2)) == x
    1

    >>> x.__setstate__({'z': 1})
    >>> x.__dict__
    {'z': 1}

    """

class Custom(Simple):

    def __new__(cls, x, y):
        r = Persistent.__new__(cls)
        r.x, r.y = x, y
        return r

    def __init__(self, x, y):
        self.a = 42

    def __getnewargs__(self):
        return self.x, self.y

    def __getstate__(self):
        return self.a

    def __setstate__(self, a):
        self.a = a


def test_pickling_w_overrides():
    """
    >>> x = Custom('x', 'y')
    >>> x.a = 99

    >>> (f, (c, ax, ay), a) = x.__reduce__()
    >>> f.__name__
    '__newobj__'
    >>> f.__module__
    'copy_reg'
    >>> c.__name__
    'Custom'
    >>> ax, ay, a
    ('x', 'y', 99)
    
    >>> pickle.loads(pickle.dumps(x)) == x
    1
    >>> pickle.loads(pickle.dumps(x, 0)) == x
    1
    >>> pickle.loads(pickle.dumps(x, 1)) == x
    1
    >>> pickle.loads(pickle.dumps(x, 2)) == x
    1
    
    """

class Slotted(Persistent):
    __slots__ = 's1', 's2', '_p_splat', '_v_eek'
    def __init__(self, s1, s2):
        self.s1, self.s2 = s1, s2
        self._v_eek = 1
        self._p_splat = 2

class SubSlotted(Slotted):
    __slots__ = 's3', 's4'
    def __init__(self, s1, s2, s3):
        Slotted.__init__(self, s1, s2)
        self.s3 = s3

        
    def __cmp__(self, other):
        return cmpattrs(self, other, '__class__', 's1', 's2', 's3', 's4')


def test_pickling_w_slots_only():
    """
    >>> x = SubSlotted('x', 'y', 'z')

    >>> x.__getnewargs__()
    ()

    >>> d, s = x.__getstate__()
    >>> d
    >>> print_dict(s)
    {'s1': 'x', 's2': 'y', 's3': 'z'}
    
    >>> pickle.loads(pickle.dumps(x)) == x
    1
    >>> pickle.loads(pickle.dumps(x, 0)) == x
    1
    >>> pickle.loads(pickle.dumps(x, 1)) == x
    1
    >>> pickle.loads(pickle.dumps(x, 2)) == x
    1

    >>> x.s4 = 'spam'
    
    >>> d, s = x.__getstate__()
    >>> d
    >>> print_dict(s)
    {'s1': 'x', 's2': 'y', 's3': 'z', 's4': 'spam'}
    
    >>> pickle.loads(pickle.dumps(x)) == x
    1
    >>> pickle.loads(pickle.dumps(x, 0)) == x
    1
    >>> pickle.loads(pickle.dumps(x, 1)) == x
    1
    >>> pickle.loads(pickle.dumps(x, 2)) == x
    1

    """

class SubSubSlotted(SubSlotted):

    def __init__(self, s1, s2, s3, **kw):
        SubSlotted.__init__(self, s1, s2, s3)
        self.__dict__.update(kw)
        self._v_favorite_color = 'blue'
        self._p_foo = 'bar'
        
    def __cmp__(self, other):
        return cmpattrs(self, other,
                        '__class__', 's1', 's2', 's3', 's4',
                        *(self.__dict__.keys()))

def test_pickling_w_slots():
    """
    >>> x = SubSubSlotted('x', 'y', 'z', aaa=1, bbb='foo')

    >>> x.__getnewargs__()
    ()

    >>> d, s = x.__getstate__()
    >>> print_dict(d)
    {'aaa': 1, 'bbb': 'foo'}
    >>> print_dict(s)
    {'s1': 'x', 's2': 'y', 's3': 'z'}
    
    >>> pickle.loads(pickle.dumps(x)) == x
    1
    >>> pickle.loads(pickle.dumps(x, 0)) == x
    1
    >>> pickle.loads(pickle.dumps(x, 1)) == x
    1
    >>> pickle.loads(pickle.dumps(x, 2)) == x
    1

    >>> x.s4 = 'spam'
    
    >>> d, s = x.__getstate__()
    >>> print_dict(d)
    {'aaa': 1, 'bbb': 'foo'}
    >>> print_dict(s)
    {'s1': 'x', 's2': 'y', 's3': 'z', 's4': 'spam'}

    >>> pickle.loads(pickle.dumps(x)) == x
    1
    >>> pickle.loads(pickle.dumps(x, 0)) == x
    1
    >>> pickle.loads(pickle.dumps(x, 1)) == x
    1
    >>> pickle.loads(pickle.dumps(x, 2)) == x
    1

    """

def test_pickling_w_slots_w_empty_dict():
    """
    >>> x = SubSubSlotted('x', 'y', 'z')

    >>> x.__getnewargs__()
    ()

    >>> d, s = x.__getstate__()
    >>> print_dict(d)
    {}
    >>> print_dict(s)
    {'s1': 'x', 's2': 'y', 's3': 'z'}
    
    >>> pickle.loads(pickle.dumps(x)) == x
    1
    >>> pickle.loads(pickle.dumps(x, 0)) == x
    1
    >>> pickle.loads(pickle.dumps(x, 1)) == x
    1
    >>> pickle.loads(pickle.dumps(x, 2)) == x
    1

    >>> x.s4 = 'spam'
    
    >>> d, s = x.__getstate__()
    >>> print_dict(d)
    {}
    >>> print_dict(s)
    {'s1': 'x', 's2': 'y', 's3': 'z', 's4': 'spam'}

    >>> pickle.loads(pickle.dumps(x)) == x
    1
    >>> pickle.loads(pickle.dumps(x, 0)) == x
    1
    >>> pickle.loads(pickle.dumps(x, 1)) == x
    1
    >>> pickle.loads(pickle.dumps(x, 2)) == x
    1

    """
    
def test_setattr_on_extension_type():
    """
    >>> for name in 'x', '_x', 'x_', '__x_y__', '___x__', '__x___', '_x_':
    ...     setattr(Persistent, name, 1)
    ...     print getattr(Persistent, name)
    ...     delattr(Persistent, name)
    ...     print getattr(Persistent, name, 0)
    1
    0
    1
    0
    1
    0
    1
    0
    1
    0
    1
    0
    1
    0

    >>> Persistent.__foo__ = 1
    Traceback (most recent call last):
    ...
    TypeError: can't set attributes of built-in/extension type """ \
        """'Persistence.Persistent' if the attribute name begins """ \
        """and ends with __ and contains only 4 _ characters

    >>> Persistent.__foo__
    Traceback (most recent call last):
    ...
    AttributeError: type object 'Persistence.Persistent' """ \
        """has no attribute '__foo__'

    >>> del Persistent.__foo__
    Traceback (most recent call last):
    ...
    TypeError: can't set attributes of built-in/extension type """ \
        """'Persistence.Persistent' if the attribute name begins """ \
        """and ends with __ and contains only 4 _ characters

    """

from doctest import DocTestSuite
import unittest

def test_suite():
    return unittest.TestSuite((
        DocTestSuite(),
        ))

if __name__ == '__main__': unittest.main()







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