58 lines
1.8 KiB
TeX
58 lines
1.8 KiB
TeX
\chapter{Evaluating expression in ``safe'' environments}
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%
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\begin{description}
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\item[Used files:] none, defined in modules.scm
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\item[Name of the package:] loser, toothless, toothless-eval \\
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(you want the last one)
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\end{description}
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%
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\section{Overview}
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\FIXME{Is toothless really R5RS, too?}
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These modules define an environment that is \RnRS without features that
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could examine or effect the file system. You can also use it as a
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model of how to execute code in other protected environments in \scm.
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\section{The \protect{\texttt{loser}} package}
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The \ex{loser} package exports only one procedure:
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\begin{defundesc}{loser}{name}{nothing}
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Raises an error like ``Illegal call \var{name}''.
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\end{defundesc}
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\section{The \protect{\texttt{toothless}} package}
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The \ex{toothless} package contains everything of \RnRS except
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that following procedure cause an error if called:
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\begin{itemize}
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\item \ex{call-with-input-file}
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\item \ex{call-with-output-file}
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\item \ex{load}
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\item \ex{open-input-file}
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\item \ex{open-output-file}
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\item \ex{transcript-on}
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\item \ex{with-input-from-file}
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\item \ex{with-input-to-file}
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\item \ex{eval}
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\item \ex{interaction-environment}
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\item \ex{scheme-report-environment}
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\end{itemize}
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So, \ex{toothless} creates an environment as described in
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\emph{Overview} above.
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\section{The \protect{\texttt{toothless-eval}} package}
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\begin{defundesc}{eval-safely} {expression} {any result}
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Creates a brand new package, imports the \ex{toothless} structure,
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and evaluates \semvar{expression} in it. When the evaluation is
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done, the environment is thrown away, so \semvar{expression}'s
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side-effects don't persist from one \ex{eval\=safely} call to the
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next. If \semvar{expression} raises an error exception, we abort and
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return \sharpf.
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\end{defundesc}
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%%% Local Variables:
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%%% mode: latex
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%%% TeX-master: t
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%%% End:
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