import inspect
import weakref
from pyramid.compat import (
integer_types,
string_types,
text_,
PY3,
)
from pyramid.path import DottedNameResolver as _DottedNameResolver
class DottedNameResolver(_DottedNameResolver):
def __init__(self, package=None): # default to package = None for bw compat
return _DottedNameResolver.__init__(self, package)
class InstancePropertyMixin(object):
""" Mixin that will allow an instance to add properties at
run-time as if they had been defined via @property or @reify
on the class itself.
"""
def set_property(self, callable, name=None, reify=False):
""" Add a callable or a property descriptor to the instance.
Properties, unlike attributes, are lazily evaluated by executing
an underlying callable when accessed. They can be useful for
adding features to an object without any cost if those features
go unused.
A property may also be reified via the
:class:`pyramid.decorator.reify` decorator by setting
``reify=True``, allowing the result of the evaluation to be
cached. Thus the value of the property is only computed once for
the lifetime of the object.
``callable`` can either be a callable that accepts the instance
as
its single positional parameter, or it can be a property
descriptor.
If the ``callable`` is a property descriptor, the ``name``
parameter must be supplied or a ``ValueError`` will be raised.
Also note that a property descriptor cannot be reified, so
``reify`` must be ``False``.
If ``name`` is None, the name of the property will be computed
from the name of the ``callable``.
.. code-block:: python
:linenos:
class Foo(InstancePropertyMixin):
_x = 1
def _get_x(self):
return _x
def _set_x(self, value):
self._x = value
foo = Foo()
foo.set_property(property(_get_x, _set_x), name='x')
foo.set_property(_get_x, name='y', reify=True)
>>> foo.x
1
>>> foo.y
1
>>> foo.x = 5
>>> foo.x
5
>>> foo.y # notice y keeps the original value
1
"""
is_property = isinstance(callable, property)
if is_property:
fn = callable
if name is None:
raise ValueError('must specify "name" for a property')
if reify:
raise ValueError('cannot reify a property')
elif name is not None:
fn = lambda this: callable(this)
fn.__name__ = name
fn.__doc__ = callable.__doc__
else:
name = callable.__name__
fn = callable
if reify:
import pyramid.decorator
fn = pyramid.decorator.reify(fn)
elif not is_property:
fn = property(fn)
attrs = { name: fn }
parent = self.__class__
cls = type(parent.__name__, (parent, object), attrs)
self.__class__ = cls
class WeakOrderedSet(object):
""" Maintain a set of items.
Each item is stored as a weakref to avoid extending their lifetime.
The values may be iterated over or the last item added may be
accessed via the ``last`` property.
If items are added more than once, the most recent addition will
be remembered in the order:
order = WeakOrderedSet()
order.add('1')
order.add('2')
order.add('1')
list(order) == ['2', '1']
order.last == '1'
"""
def __init__(self):
self._items = {}
self._order = []
def add(self, item):
""" Add an item to the set."""
oid = id(item)
if oid in self._items:
self._order.remove(oid)
self._order.append(oid)
return
ref = weakref.ref(item, lambda x: self.remove(item))
self._items[oid] = ref
self._order.append(oid)
def remove(self, item):
""" Remove an item from the set."""
oid = id(item)
if oid in self._items:
del self._items[oid]
self._order.remove(oid)
def empty(self):
""" Clear all objects from the set."""
self._items = {}
self._order = []
def __len__(self):
return len(self._order)
def __contains__(self, item):
oid = id(item)
return oid in self._items
def __iter__(self):
return (self._items[oid]() for oid in self._order)
@property
def last(self):
if self._order:
oid = self._order[-1]
return self._items[oid]()
def strings_differ(string1, string2):
"""Check whether two strings differ while avoiding timing attacks.
This function returns True if the given strings differ and False
if they are equal. It's careful not to leak information about *where*
they differ as a result of its running time, which can be very important
to avoid certain timing-related crypto attacks:
http://seb.dbzteam.org/crypto/python-oauth-timing-hmac.pdf
"""
if len(string1) != len(string2):
return True
invalid_bits = 0
for a, b in zip(string1, string2):
invalid_bits += a != b
return invalid_bits != 0
def object_description(object):
""" Produce a human-consumable text description of ``object``,
usually involving a Python dotted name. For example:
.. code-block:: python
>>> object_description(None)
u'None'
>>> from xml.dom import minidom
>>> object_description(minidom)
u'module xml.dom.minidom'
>>> object_description(minidom.Attr)
u'class xml.dom.minidom.Attr'
>>> object_description(minidom.Attr.appendChild)
u'method appendChild of class xml.dom.minidom.Attr'
>>>
If this method cannot identify the type of the object, a generic
description ala ``object <object.__name__>`` will be returned.
If the object passed is already a string, it is simply returned. If it
is a boolean, an integer, a list, a tuple, a set, or ``None``, a
(possibly shortened) string representation is returned.
"""
if isinstance(object, string_types):
return text_(object)
if isinstance(object, integer_types):
return text_(str(object))
if isinstance(object, (bool, float, type(None))):
return text_(str(object))
if isinstance(object, set):
if PY3: # pragma: no cover
return shortrepr(object, '}')
else:
return shortrepr(object, ')')
if isinstance(object, tuple):
return shortrepr(object, ')')
if isinstance(object, list):
return shortrepr(object, ']')
if isinstance(object, dict):
return shortrepr(object, '}')
module = inspect.getmodule(object)
if module is None:
return text_('object %s' % str(object))
modulename = module.__name__
if inspect.ismodule(object):
return text_('module %s' % modulename)
if inspect.ismethod(object):
oself = getattr(object, '__self__', None)
if oself is None: # pragma: no cover
oself = getattr(object, 'im_self', None)
return text_('method %s of class %s.%s' %
(object.__name__, modulename,
oself.__class__.__name__))
if inspect.isclass(object):
dottedname = '%s.%s' % (modulename, object.__name__)
return text_('class %s' % dottedname)
if inspect.isfunction(object):
dottedname = '%s.%s' % (modulename, object.__name__)
return text_('function %s' % dottedname)
return text_('object %s' % str(object))
def shortrepr(object, closer):
r = str(object)
if len(r) > 100:
r = r[:100] + ' ... %s' % closer
return r
