1 2:mod:`Bastion` --- Restricting access to objects 3================================================ 4 5.. module:: Bastion 6 :synopsis: Providing restricted access to objects. 7 :deprecated: 8 9.. deprecated:: 2.6 10 The :mod:`Bastion` module has been removed in Python 3. 11 12.. moduleauthor:: Barry Warsaw <bwarsaw@python.org> 13 14 15.. versionchanged:: 2.3 16 Disabled module. 17 18.. note:: 19 20 The documentation has been left in place to help in reading old code that uses 21 the module. 22 23According to the dictionary, a bastion is "a fortified area or position", or 24"something that is considered a stronghold." It's a suitable name for this 25module, which provides a way to forbid access to certain attributes of an 26object. It must always be used with the :mod:`rexec` module, in order to allow 27restricted-mode programs access to certain safe attributes of an object, while 28denying access to other, unsafe attributes. 29 30.. I'm concerned that the word 'bastion' won't be understood by people 31.. for whom English is a second language, making the module name 32.. somewhat mysterious. Thus, the brief definition... --amk 33 34.. I've punted on the issue of documenting keyword arguments for now. 35 36 37.. function:: Bastion(object[, filter[, name[, class]]]) 38 39 Protect the object *object*, returning a bastion for the object. Any attempt to 40 access one of the object's attributes will have to be approved by the *filter* 41 function; if the access is denied an :exc:`AttributeError` exception will be 42 raised. 43 44 If present, *filter* must be a function that accepts a string containing an 45 attribute name, and returns true if access to that attribute will be permitted; 46 if *filter* returns false, the access is denied. The default filter denies 47 access to any function beginning with an underscore (``'_'``). The bastion's 48 string representation will be ``<Bastion for name>`` if a value for *name* is 49 provided; otherwise, ``repr(object)`` will be used. 50 51 *class*, if present, should be a subclass of :class:`BastionClass`; see the 52 code in :file:`bastion.py` for the details. Overriding the default 53 :class:`BastionClass` will rarely be required. 54 55 56.. class:: BastionClass(getfunc, name) 57 58 Class which actually implements bastion objects. This is the default class used 59 by :func:`Bastion`. The *getfunc* parameter is a function which returns the 60 value of an attribute which should be exposed to the restricted execution 61 environment when called with the name of the attribute as the only parameter. 62 *name* is used to construct the :func:`repr` of the :class:`BastionClass` 63 instance. 64 65