131 lines
6.3 KiB
HTML
131 lines
6.3 KiB
HTML
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<!DOCTYPE html>
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<html>
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<!-- Created by GNU Texinfo 7.1, https://www.gnu.org/software/texinfo/ -->
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
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<!-- This manual documents Guile version 3.0.10.
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Copyright (C) 1996-1997, 2000-2005, 2009-2023 Free Software Foundation,
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Inc.
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Copyright (C) 2021 Maxime Devos
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Copyright (C) 2024 Tomas Volf
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Permission is granted to copy, distribute and/or modify this document
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under the terms of the GNU Free Documentation License, Version 1.3 or
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any later version published by the Free Software Foundation; with no
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Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A
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copy of the license is included in the section entitled "GNU Free
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Documentation License." -->
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<title>Standard Error Handling (Guile Reference Manual)</title>
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<meta name="description" content="Standard Error Handling (Guile Reference Manual)">
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<meta name="keywords" content="Standard Error Handling (Guile Reference Manual)">
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<meta name="viewport" content="width=device-width,initial-scale=1">
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<link href="index.html" rel="start" title="Top">
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<link href="Concept-Index.html" rel="index" title="Concept Index">
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<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
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<link href="Programmatic-Error-Handling.html" rel="up" title="Programmatic Error Handling">
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<link href="Stack-Overflow.html" rel="next" title="Stack Overflow">
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<link href="Pre_002dUnwind-Debugging.html" rel="prev" title="Pre-Unwind Debugging">
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<style type="text/css">
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</style>
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<link rel="stylesheet" type="text/css" href="https://www.gnu.org/software/gnulib/manual.css">
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</head>
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<body lang="en">
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<div class="subsubsection-level-extent" id="Standard-Error-Handling">
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<div class="nav-panel">
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<p>
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Next: <a href="Stack-Overflow.html" accesskey="n" rel="next">Stack Overflow</a>, Previous: <a href="Pre_002dUnwind-Debugging.html" accesskey="p" rel="prev">Pre-Unwind Debugging</a>, Up: <a href="Programmatic-Error-Handling.html" accesskey="u" rel="up">Programmatic Error Handling</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html" title="Index" rel="index">Index</a>]</p>
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</div>
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<hr>
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<h4 class="subsubsection" id="call_002dwith_002derror_002dhandling"><span>6.26.3.3 call-with-error-handling<a class="copiable-link" href="#call_002dwith_002derror_002dhandling"> ¶</a></span></h4>
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<p>The Guile REPL code (in <samp class="file">system/repl/repl.scm</samp> and related files)
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uses a <code class="code">catch</code> with a pre-unwind handler to capture the stack when
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an error occurs in an expression that was typed into the REPL, and debug
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that stack interactively in the context of the error.
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</p>
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<p>These procedures are available for use by user programs, in the
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<code class="code">(system repl error-handling)</code> module.
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</p>
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<div class="example lisp">
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<pre class="lisp-preformatted">(use-modules (system repl error-handling))
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</pre></div>
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<dl class="first-deffn">
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<dt class="deffn" id="index-call_002dwith_002derror_002dhandling"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">call-with-error-handling</strong> <var class="def-var-arguments">thunk [#:on-error on-error=’debug] [#:post-error post-error=’catch] [#:pass-keys pass-keys=’(quit)] [#:report-keys report-keys=’(stack-overflow)] [#:trap-handler trap-handler=’debug]</var><a class="copiable-link" href="#index-call_002dwith_002derror_002dhandling"> ¶</a></span></dt>
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<dd><p>Call a thunk in a context in which errors are handled.
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</p>
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<p>Note that this function was written when <code class="code">throw</code>/<code class="code">catch</code> were
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the fundamental exception handling primitives in Guile, and so exposes
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some aspects of that interface (notably in the form of the procedural
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handlers). Guile will probably replace this function with a
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<code class="code">call-with-standard-exception-handling</code> in the future.
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</p>
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<p>There are five keyword arguments:
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</p>
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<dl class="table">
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<dt><var class="var">on-error</var></dt>
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<dd><p>Specifies what to do before the stack is unwound.
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</p>
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<p>Valid options are <code class="code">debug</code> (the default), which will enter a
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debugger; <code class="code">pass</code>, in which case nothing is done, and the exception
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is rethrown; or a procedure, which will be the pre-unwind handler.
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</p>
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</dd>
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<dt><var class="var">post-error</var></dt>
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<dd><p>Specifies what to do after the stack is unwound.
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</p>
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<p>Valid options are <code class="code">catch</code> (the default), which will silently catch
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errors, returning the unspecified value; <code class="code">report</code>, which prints out
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a description of the error (via <code class="code">display-error</code>), and then returns
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the unspecified value; or a procedure, which will be the catch handler.
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</p>
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</dd>
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<dt><var class="var">trap-handler</var></dt>
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<dd><p>Specifies a trap handler: what to do when a breakpoint is hit.
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</p>
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<p>Valid options are <code class="code">debug</code>, which will enter the debugger;
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<code class="code">pass</code>, which does nothing; or <code class="code">disabled</code>, which disables
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traps entirely. See <a class="xref" href="Traps.html">Traps</a>, for more information.
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</p>
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</dd>
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<dt><var class="var">pass-keys</var></dt>
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<dd><p>A set of keys to ignore, as a list.
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</p>
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</dd>
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<dt><var class="var">report-keys</var></dt>
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<dd><p>A set of keys to always report even if the post-error handler is
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<code class="code">catch</code>, as a list.
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</p></dd>
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</dl>
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</dd></dl>
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</div>
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<hr>
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<div class="nav-panel">
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<p>
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Next: <a href="Stack-Overflow.html">Stack Overflow</a>, Previous: <a href="Pre_002dUnwind-Debugging.html">Pre-Unwind Debugging</a>, Up: <a href="Programmatic-Error-Handling.html">Programmatic Error Handling</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html" title="Index" rel="index">Index</a>]</p>
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</div>
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</body>
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</html>
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