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| <h5 class="subsubsection">23.3.3.4 Guile Exception Handling</h5> |
| |
| <p><a name="index-guile-exceptions-2473"></a><a name="index-exceptions_002c-guile-2474"></a><a name="index-set-guile-print_002dstack-2475"></a> |
| When executing the <code>guile</code> command, Guile exceptions |
| uncaught within the Guile code are translated to calls to the |
| <span class="sc">gdb</span> error-reporting mechanism. If the command that called |
| <code>guile</code> does not handle the error, <span class="sc">gdb</span> will |
| terminate it and report the error according to the setting of |
| the <code>guile print-stack</code> parameter. |
| |
| <p>The <code>guile print-stack</code> parameter has three settings: |
| |
| <dl> |
| <dt><code>none</code><dd>Nothing is printed. |
| |
| <br><dt><code>message</code><dd>An error message is printed containing the Guile exception name, |
| the associated value, and the Guile call stack backtrace at the |
| point where the exception was raised. Example: |
| |
| <pre class="smallexample"> (gdb) guile (display foo) |
| ERROR: In procedure memoize-variable-access!: |
| ERROR: Unbound variable: foo |
| Error while executing Scheme code. |
| </pre> |
| <br><dt><code>full</code><dd>In addition to an error message a full backtrace is printed. |
| |
| <pre class="smallexample"> (gdb) set guile print-stack full |
| (gdb) guile (display foo) |
| Guile Backtrace: |
| In ice-9/boot-9.scm: |
| 157: 10 [catch #t #<catch-closure 2c76e20> ...] |
| In unknown file: |
| ?: 9 [apply-smob/1 #<catch-closure 2c76e20>] |
| In ice-9/boot-9.scm: |
| 157: 8 [catch #t #<catch-closure 2c76d20> ...] |
| In unknown file: |
| ?: 7 [apply-smob/1 #<catch-closure 2c76d20>] |
| ?: 6 [call-with-input-string "(display foo)" ...] |
| In ice-9/boot-9.scm: |
| 2320: 5 [save-module-excursion #<procedure 2c2dc30 ... ()>] |
| In ice-9/eval-string.scm: |
| 44: 4 [read-and-eval #<input: string 27cb410> #:lang ...] |
| 37: 3 [lp (display foo)] |
| In ice-9/eval.scm: |
| 387: 2 [eval # ()] |
| 393: 1 [eval #<memoized foo> ()] |
| In unknown file: |
| ?: 0 [memoize-variable-access! #<memoized foo> ...] |
| |
| ERROR: In procedure memoize-variable-access!: |
| ERROR: Unbound variable: foo |
| Error while executing Scheme code. |
| </pre> |
| </dl> |
| |
| <p><span class="sc">gdb</span> errors that happen in <span class="sc">gdb</span> commands invoked by |
| Guile code are converted to Guile exceptions. The type of the |
| Guile exception depends on the error. |
| |
| <p>Guile procedures provided by <span class="sc">gdb</span> can throw the standard |
| Guile exceptions like <code>wrong-type-arg</code> and <code>out-of-range</code>. |
| |
| <p>User interrupt (via <kbd>C-c</kbd> or by typing <kbd>q</kbd> at a pagination |
| prompt) is translated to a Guile <code>signal</code> exception with value |
| <code>SIGINT</code>. |
| |
| <p><span class="sc">gdb</span> Guile procedures can also throw these exceptions: |
| |
| <dl> |
| <dt><code>gdb:error</code><a name="index-gdb_003aerror-2476"></a><dd>This exception is a catch-all for errors generated from within <span class="sc">gdb</span>. |
| |
| <br><dt><code>gdb:invalid-object</code><a name="index-gdb_003ainvalid_002dobject-2477"></a><dd>This exception is thrown when accessing Guile objects that wrap underlying |
| <span class="sc">gdb</span> objects have become invalid. For example, a |
| <code><gdb:breakpoint></code> object becomes invalid if the user deletes it |
| from the command line. The object still exists in Guile, but the |
| object it represents is gone. Further operations on this breakpoint |
| will throw this exception. |
| |
| <br><dt><code>gdb:memory-error</code><a name="index-gdb_003amemory_002derror-2478"></a><dd>This exception is thrown when an operation tried to access invalid |
| memory in the inferior. |
| |
| <br><dt><code>gdb:pp-type-error</code><a name="index-gdb_003app_002dtype_002derror-2479"></a><dd>This exception is thrown when a Guile pretty-printer passes a bad object |
| to <span class="sc">gdb</span>. |
| </dl> |
| |
| <p>The following exception-related procedures are provided by the |
| <code>(gdb)</code> module. |
| |
| <div class="defun"> |
| — Scheme Procedure: <b>make-exception</b><var> key args<a name="index-make_002dexception-2480"></a></var><br> |
| <blockquote><p>Return a <code><gdb:exception></code> object given by its <var>key</var> and |
| <var>args</var>, which are the standard Guile parameters of an exception. |
| See the Guile documentation for more information (see <a href="../guile/Exceptions.html#Exceptions">Exceptions</a>). |
| </p></blockquote></div> |
| |
| <div class="defun"> |
| — Scheme Procedure: <b>exception?</b><var> object<a name="index-exception_003f-2481"></a></var><br> |
| <blockquote><p>Return <code>#t</code> if <var>object</var> is a <code><gdb:exception></code> object. |
| Otherwise return <code>#f</code>. |
| </p></blockquote></div> |
| |
| <div class="defun"> |
| — Scheme Procedure: <b>exception-key</b><var> exception<a name="index-exception_002dkey-2482"></a></var><br> |
| <blockquote><p>Return the <var>args</var> field of a <code><gdb:exception></code> object. |
| </p></blockquote></div> |
| |
| <div class="defun"> |
| — Scheme Procedure: <b>exception-args</b><var> exception<a name="index-exception_002dargs-2483"></a></var><br> |
| <blockquote><p>Return the <var>args</var> field of a <code><gdb:exception></code> object. |
| </p></blockquote></div> |
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