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<title>Debugging with GDB: Finish Breakpoints in Python</title>
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<a name="Finish-Breakpoints-in-Python"></a>
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<p>
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Next: <a href="Lazy-Strings-In-Python.html#Lazy-Strings-In-Python" accesskey="n" rel="next">Lazy Strings In Python</a>, Previous: <a href="Breakpoints-In-Python.html#Breakpoints-In-Python" accesskey="p" rel="previous">Breakpoints In Python</a>, Up: <a href="Python-API.html#Python-API" accesskey="u" rel="up">Python API</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html#Concept-Index" title="Index" rel="index">Index</a>]</p>
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<a name="Finish-Breakpoints"></a>
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<h4 class="subsubsection">23.2.2.31 Finish Breakpoints</h4>
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<a name="index-python-finish-breakpoints"></a>
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<a name="index-gdb_002eFinishBreakpoint"></a>
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<p>A finish breakpoint is a temporary breakpoint set at the return address of
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a frame, based on the <code>finish</code> command. <code>gdb.FinishBreakpoint</code>
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extends <code>gdb.Breakpoint</code>. The underlying breakpoint will be disabled
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and deleted when the execution will run out of the breakpoint scope (i.e.
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<code>Breakpoint.stop</code> or <code>FinishBreakpoint.out_of_scope</code> triggered).
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Finish breakpoints are thread specific and must be create with the right
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thread selected.
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</p>
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<dl>
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<dt><a name="index-FinishBreakpoint_002e_005f_005finit_005f_005f"></a>Function: <strong>FinishBreakpoint.__init__</strong> <em>(<span class="roman">[</span>frame<span class="roman">]</span> <span class="roman">[</span>, internal<span class="roman">]</span>)</em></dt>
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<dd><p>Create a finish breakpoint at the return address of the <code>gdb.Frame</code>
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object <var>frame</var>. If <var>frame</var> is not provided, this defaults to the
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newest frame. The optional <var>internal</var> argument allows the breakpoint to
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become invisible to the user. See <a href="Breakpoints-In-Python.html#Breakpoints-In-Python">Breakpoints In Python</a>, for further
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details about this argument.
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</p></dd></dl>
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<dl>
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<dt><a name="index-FinishBreakpoint_002eout_005fof_005fscope"></a>Function: <strong>FinishBreakpoint.out_of_scope</strong> <em>(self)</em></dt>
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<dd><p>In some circumstances (e.g. <code>longjmp</code>, C<tt>++</tt> exceptions, <small>GDB</small>
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<code>return</code> command, …), a function may not properly terminate, and
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thus never hit the finish breakpoint. When <small>GDB</small> notices such a
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situation, the <code>out_of_scope</code> callback will be triggered.
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</p>
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<p>You may want to sub-class <code>gdb.FinishBreakpoint</code> and override this
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method:
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</p>
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<div class="smallexample">
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<pre class="smallexample">class MyFinishBreakpoint (gdb.FinishBreakpoint)
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def stop (self):
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print "normal finish"
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return True
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def out_of_scope ():
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print "abnormal finish"
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</pre></div>
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</dd></dl>
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<dl>
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<dt><a name="index-FinishBreakpoint_002ereturn_005fvalue"></a>Variable: <strong>FinishBreakpoint.return_value</strong></dt>
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<dd><p>When <small>GDB</small> is stopped at a finish breakpoint and the frame
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used to build the <code>gdb.FinishBreakpoint</code> object had debug symbols, this
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attribute will contain a <code>gdb.Value</code> object corresponding to the return
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value of the function. The value will be <code>None</code> if the function return
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type is <code>void</code> or if the return value was not computable. This attribute
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is not writable.
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</p></dd></dl>
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Next: <a href="Lazy-Strings-In-Python.html#Lazy-Strings-In-Python" accesskey="n" rel="next">Lazy Strings In Python</a>, Previous: <a href="Breakpoints-In-Python.html#Breakpoints-In-Python" accesskey="p" rel="previous">Breakpoints In Python</a>, Up: <a href="Python-API.html#Python-API" accesskey="u" rel="up">Python API</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html#Concept-Index" title="Index" rel="index">Index</a>]</p>
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