Coverage for local/lib/python2.7/site-packages/sage/misc/test_class_pickling.py : 100%

from __future__ import absolute_import 

class bar: 

pass 

def metaclass(name, bases): 

""" 

Creates a new class in this metaclass 

INPUT: 

- name -- a string 

- bases -- a tuple of classes 

EXAMPLES:: 

sage: from sage.misc.test_class_pickling import metaclass, bar 

sage: c = metaclass("foo2", (object, bar,)) 

constructing class 

sage: c 

<class 'sage.misc.test_class_pickling.foo2'> 

sage: type(c) 

<class 'sage.misc.test_class_pickling.Metaclass'> 

sage: c.__bases__ 

(<... 'object'>, <class sage.misc.test_class_pickling.bar at ...>) 

""" 

print("constructing class") 

result = Metaclass(name, bases, dict()) 

result.reduce_args = (name, bases) 

return result 

class Metaclass(type): 

""" 

This metaclass illustrates the customization of how a class is pickled. 

It requires a slightly patched version of cPickle. 

See: 

- https://docs.python.org/3/library/copyreg.html#module-copyreg 

- http://groups.google.com/group/comp.lang.python/browse_thread/thread/66c282afc04aa39c/ 

- http://groups.google.com/group/sage-devel/browse_thread/thread/583048dc7d373d6a/ 

EXAMPLES:: 

sage: from sage.misc.test_class_pickling import metaclass, bar 

sage: c = metaclass("foo", (object, bar,)) 

constructing class 

sage: from six.moves import cPickle 

sage: s = cPickle.dumps(c) 

reducing a class 

sage: c2 = cPickle.loads(s) 

constructing class 

sage: c == c2 

calling __eq__ defined in Metaclass 

True 

""" 

def __eq__(self, other): 

print("calling __eq__ defined in Metaclass") 

return (type(self) is type(other)) and (self.reduce_args == other.reduce_args) 

def __reduce__(self): 

""" 

Implement the pickle protocol for classes in this metaclass 

(not for the instances of this class!!!) 

EXAMPLES:: 

sage: from sage.misc.test_class_pickling import metaclass, bar 

sage: c = metaclass("foo3", (object, bar,)) 

constructing class 

sage: c.__class__.__reduce__(c) 

reducing a class 

(<function metaclass at ...>, ('foo3', (<... 'object'>, <class sage.misc.test_class_pickling.bar at ...>))) 

""" 

print("reducing a class") 

return (metaclass, self.reduce_args) 

from six.moves import copyreg 

copyreg.pickle(Metaclass, Metaclass.__reduce__)