| <html lang="en"> |
| <head> |
| <title>Exception Handling - Debugging with GDB</title> |
| <meta http-equiv="Content-Type" content="text/html"> |
| <meta name="description" content="Debugging with GDB"> |
| <meta name="generator" content="makeinfo 4.13"> |
| <link title="Top" rel="start" href="index.html#Top"> |
| <link rel="up" href="Python-API.html#Python-API" title="Python API"> |
| <link rel="prev" href="Basic-Python.html#Basic-Python" title="Basic Python"> |
| <link rel="next" href="Values-From-Inferior.html#Values-From-Inferior" title="Values From Inferior"> |
| <link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage"> |
| <!-- |
| Copyright (C) 1988-2019 Free Software Foundation, Inc. |
| |
| Permission is granted to copy, distribute and/or modify this document |
| under the terms of the GNU Free Documentation License, Version 1.3 or |
| any later version published by the Free Software Foundation; with the |
| Invariant Sections being ``Free Software'' and ``Free Software Needs |
| Free Documentation'', with the Front-Cover Texts being ``A GNU Manual,'' |
| and with the Back-Cover Texts as in (a) below. |
| |
| (a) The FSF's Back-Cover Text is: ``You are free to copy and modify |
| this GNU Manual. Buying copies from GNU Press supports the FSF in |
| developing GNU and promoting software freedom.'' |
| --> |
| <meta http-equiv="Content-Style-Type" content="text/css"> |
| <style type="text/css"><!-- |
| pre.display { font-family:inherit } |
| pre.format { font-family:inherit } |
| pre.smalldisplay { font-family:inherit; font-size:smaller } |
| pre.smallformat { font-family:inherit; font-size:smaller } |
| pre.smallexample { font-size:smaller } |
| pre.smalllisp { font-size:smaller } |
| span.sc { font-variant:small-caps } |
| span.roman { font-family:serif; font-weight:normal; } |
| span.sansserif { font-family:sans-serif; font-weight:normal; } |
| --></style> |
| </head> |
| <body> |
| <div class="node"> |
| <a name="Exception-Handling"></a> |
| <p> |
| Next: <a rel="next" accesskey="n" href="Values-From-Inferior.html#Values-From-Inferior">Values From Inferior</a>, |
| Previous: <a rel="previous" accesskey="p" href="Basic-Python.html#Basic-Python">Basic Python</a>, |
| Up: <a rel="up" accesskey="u" href="Python-API.html#Python-API">Python API</a> |
| <hr> |
| </div> |
| |
| <h5 class="subsubsection">23.2.2.2 Exception Handling</h5> |
| |
| <p><a name="index-python-exceptions-1899"></a><a name="index-exceptions_002c-python-1900"></a> |
| When executing the <code>python</code> command, Python exceptions |
| uncaught within the Python code are translated to calls to |
| <span class="sc">gdb</span> error-reporting mechanism. If the command that called |
| <code>python</code> does not handle the error, <span class="sc">gdb</span> will |
| terminate it and print an error message containing the Python |
| exception name, the associated value, and the Python call stack |
| backtrace at the point where the exception was raised. Example: |
| |
| <pre class="smallexample"> (gdb) python print foo |
| Traceback (most recent call last): |
| File "<string>", line 1, in <module> |
| NameError: name 'foo' is not defined |
| </pre> |
| <p><span class="sc">gdb</span> errors that happen in <span class="sc">gdb</span> commands invoked by |
| Python code are converted to Python exceptions. The type of the |
| Python exception depends on the error. |
| |
| <dl> |
| <dt><code>gdb.error</code><a name="index-gdb_002eerror-1901"></a><dd>This is the base class for most exceptions generated by <span class="sc">gdb</span>. |
| It is derived from <code>RuntimeError</code>, for compatibility with earlier |
| versions of <span class="sc">gdb</span>. |
| |
| <p>If an error occurring in <span class="sc">gdb</span> does not fit into some more |
| specific category, then the generated exception will have this type. |
| |
| <br><dt><code>gdb.MemoryError</code><a name="index-gdb_002eMemoryError-1902"></a><dd>This is a subclass of <code>gdb.error</code> which is thrown when an |
| operation tried to access invalid memory in the inferior. |
| |
| <br><dt><code>KeyboardInterrupt</code><a name="index-KeyboardInterrupt-1903"></a><dd>User interrupt (via <kbd>C-c</kbd> or by typing <kbd>q</kbd> at a pagination |
| prompt) is translated to a Python <code>KeyboardInterrupt</code> exception. |
| </dl> |
| |
| <p>In all cases, your exception handler will see the <span class="sc">gdb</span> error |
| message as its value and the Python call stack backtrace at the Python |
| statement closest to where the <span class="sc">gdb</span> error occured as the |
| traceback. |
| |
| <p>When implementing <span class="sc">gdb</span> commands in Python via |
| <code>gdb.Command</code>, or functions via <code>gdb.Function</code>, it is useful |
| to be able to throw an exception that doesn't cause a traceback to be |
| printed. For example, the user may have invoked the command |
| incorrectly. <span class="sc">gdb</span> provides a special exception class that can |
| be used for this purpose. |
| |
| <dl> |
| <dt><code>gdb.GdbError</code><a name="index-gdb_002eGdbError-1904"></a><dd>When thrown from a command or function, this exception will cause the |
| command or function to fail, but the Python stack will not be |
| displayed. <span class="sc">gdb</span> does not throw this exception itself, but |
| rather recognizes it when thrown from user Python code. Example: |
| |
| <pre class="smallexample"> (gdb) python |
| >class HelloWorld (gdb.Command): |
| > """Greet the whole world.""" |
| > def __init__ (self): |
| > super (HelloWorld, self).__init__ ("hello-world", gdb.COMMAND_USER) |
| > def invoke (self, args, from_tty): |
| > argv = gdb.string_to_argv (args) |
| > if len (argv) != 0: |
| > raise gdb.GdbError ("hello-world takes no arguments") |
| > print "Hello, World!" |
| >HelloWorld () |
| >end |
| (gdb) hello-world 42 |
| hello-world takes no arguments |
| </pre> |
| </dl> |
| |
| </body></html> |
| |
