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annotate Doc/lib/libbastion.tex @ 5817:48b94de85bf3 legacy-trunk

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Extensive changes by AMK.
author Guido van Rossum <guido@python.org>
date Thu, 17 Jul 1997 16:29:42 +0000
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1 \section{Standard Module \sectcode{Bastion}}
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2 \stmodindex{Bastion}
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3 \renewcommand{\indexsubitem}{(in module Bastion)}
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4
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5 % I'm concerned that the word 'bastion' won't be understood by people
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6 % for whom English is a second language, making the module name
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7 % somewhat mysterious. Thus, the brief definition... --amk
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8
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9 According to the dictionary, a bastion is ``a fortified area or
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10 position'', or ``something that is considered a stronghold.'' It's a
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11 suitable name for this module, which provides a way to forbid access
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12 to certain attributes of an object. It must always be used with the
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13 \code{rexec} module, in order to allow restricted-mode programs access
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14 to certain safe attributes of an object, while denying access to
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15 other, unsafe attributes.
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16
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17 % I've punted on the issue of documenting keyword arguments for now.
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18
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19 \begin{funcdesc}{Bastion}{object\optional{\, filter\, name\, class}}
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20 Protect the class instance \var{object}, returning a bastion for the
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21 object. Any attempt to access one of the object's attributes will
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22 have to be approved by the \var{filter} function; if the access is
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23 denied an AttributeError exception will be raised.
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24
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25 If present, \var{filter} must be a function that accepts a string
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26 containing an attribute name, and returns true if access to that
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27 attribute will be permitted; if \var{filter} returns false, the access
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28 is denied. The default filter denies access to any function beginning
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29 with an underscore (\code{_}). The bastion's string representation
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30 will be \code{<Bastion for \var{name}>} if a value for
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31 \var{name} is provided; otherwise, \code{repr(\var{object})} will be used.
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32
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33 \var{class}, if present, would be a subclass of \code{BastionClass};
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34 see the code in \file{bastion.py} for the details. Overriding the
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35 default \code{BastionClass} will rarely be required.
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36
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37 \end{funcdesc}