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| <a name="Guile-Exception-Handling"></a> |
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| <a name="Guile-Exception-Handling-1"></a> |
| <h4 class="subsubsection">23.3.3.4 Guile Exception Handling</h4> |
| <a name="index-guile-exceptions"></a> |
| <a name="index-exceptions_002c-guile"></a> |
| <a name="index-set-guile-print_002dstack"></a> |
| |
| <p>When executing the <code>guile</code> command, Guile exceptions |
| uncaught within the Guile code are translated to calls to the |
| <small>GDB</small> error-reporting mechanism. If the command that called |
| <code>guile</code> does not handle the error, <small>GDB</small> will |
| terminate it and report the error according to the setting of |
| the <code>guile print-stack</code> parameter. |
| </p> |
| <p>The <code>guile print-stack</code> parameter has three settings: |
| </p> |
| <dl compact="compact"> |
| <dt><code>none</code></dt> |
| <dd><p>Nothing is printed. |
| </p> |
| </dd> |
| <dt><code>message</code></dt> |
| <dd><p>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: |
| </p> |
| <div class="smallexample"> |
| <pre class="smallexample">(gdb) guile (display foo) |
| ERROR: In procedure memoize-variable-access!: |
| ERROR: Unbound variable: foo |
| Error while executing Scheme code. |
| </pre></div> |
| |
| </dd> |
| <dt><code>full</code></dt> |
| <dd><p>In addition to an error message a full backtrace is printed. |
| </p> |
| <div class="smallexample"> |
| <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></div> |
| </dd> |
| </dl> |
| |
| <p><small>GDB</small> errors that happen in <small>GDB</small> commands invoked by |
| Guile code are converted to Guile exceptions. The type of the |
| Guile exception depends on the error. |
| </p> |
| <p>Guile procedures provided by <small>GDB</small> can throw the standard |
| Guile exceptions like <code>wrong-type-arg</code> and <code>out-of-range</code>. |
| </p> |
| <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> |
| <p><small>GDB</small> Guile procedures can also throw these exceptions: |
| </p> |
| <dl compact="compact"> |
| <dt><code>gdb:error</code> |
| <a name="index-gdb_003aerror"></a> |
| </dt> |
| <dd><p>This exception is a catch-all for errors generated from within <small>GDB</small>. |
| </p> |
| </dd> |
| <dt><code>gdb:invalid-object</code> |
| <a name="index-gdb_003ainvalid_002dobject"></a> |
| </dt> |
| <dd><p>This exception is thrown when accessing Guile objects that wrap underlying |
| <small>GDB</small> 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. |
| </p> |
| </dd> |
| <dt><code>gdb:memory-error</code> |
| <a name="index-gdb_003amemory_002derror"></a> |
| </dt> |
| <dd><p>This exception is thrown when an operation tried to access invalid |
| memory in the inferior. |
| </p> |
| </dd> |
| <dt><code>gdb:pp-type-error</code> |
| <a name="index-gdb_003app_002dtype_002derror"></a> |
| </dt> |
| <dd><p>This exception is thrown when a Guile pretty-printer passes a bad object |
| to <small>GDB</small>. |
| </p></dd> |
| </dl> |
| |
| <p>The following exception-related procedures are provided by the |
| <code>(gdb)</code> module. |
| </p> |
| <dl> |
| <dt><a name="index-make_002dexception"></a>Scheme Procedure: <strong>make-exception</strong> <em>key args</em></dt> |
| <dd><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="http://www.gnu.org/software/guile/manual/html_node/Exceptions.html#Exceptions">Exceptions</a> in <cite>GNU Guile Reference Manual</cite>). |
| </p></dd></dl> |
| |
| <dl> |
| <dt><a name="index-exception_003f"></a>Scheme Procedure: <strong>exception?</strong> <em>object</em></dt> |
| <dd><p>Return <code>#t</code> if <var>object</var> is a <code><gdb:exception></code> object. |
| Otherwise return <code>#f</code>. |
| </p></dd></dl> |
| |
| <dl> |
| <dt><a name="index-exception_002dkey"></a>Scheme Procedure: <strong>exception-key</strong> <em>exception</em></dt> |
| <dd><p>Return the <var>args</var> field of a <code><gdb:exception></code> object. |
| </p></dd></dl> |
| |
| <dl> |
| <dt><a name="index-exception_002dargs"></a>Scheme Procedure: <strong>exception-args</strong> <em>exception</em></dt> |
| <dd><p>Return the <var>args</var> field of a <code><gdb:exception></code> object. |
| </p></dd></dl> |
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