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| <h5 class="subsubsection">23.2.2.15 Accessing inferior stack frames from Python.</h5> |
| |
| <p><a name="index-frames-in-python-1817"></a>When the debugged program stops, <span class="sc">gdb</span> is able to analyze its call |
| stack (see <a href="Frames.html#Frames">Stack frames</a>). The <code>gdb.Frame</code> class |
| represents a frame in the stack. A <code>gdb.Frame</code> object is only valid |
| while its corresponding frame exists in the inferior's stack. If you try |
| to use an invalid frame object, <span class="sc">gdb</span> will throw a <code>RuntimeError</code> |
| exception. |
| |
| <p>Two <code>gdb.Frame</code> objects can be compared for equality with the <code>==</code> |
| operator, like: |
| |
| <pre class="smallexample"> (gdb) python print gdb.newest_frame() == gdb.selected_frame () |
| True |
| </pre> |
| <p>The following frame-related functions are available in the <code>gdb</code> module: |
| |
| <p><a name="index-gdb_002eselected_005fframe-1818"></a> |
| |
| <div class="defun"> |
| — Function: <b>selected_frame</b><var><a name="index-selected_005fframe-1819"></a></var><br> |
| <blockquote><p>Return the selected frame object. (see <a href="Selection.html#Selection">Selecting a Frame</a>). |
| </p></blockquote></div> |
| |
| <div class="defun"> |
| — Function: <b>frame_stop_reason_string</b><var> reason<a name="index-frame_005fstop_005freason_005fstring-1820"></a></var><br> |
| <blockquote><p>Return a string explaining the reason why <span class="sc">gdb</span> stopped unwinding |
| frames, as expressed by the given <var>reason</var> code (an integer, see the |
| <code>unwind_stop_reason</code> method further down in this section). |
| </p></blockquote></div> |
| |
| <p>A <code>gdb.Frame</code> object has the following methods: |
| |
| <dl> |
| |
| <div class="defun"> |
| — Method on Frame: <b>is_valid</b><var><a name="index-is_005fvalid-on-Frame-1821"></a></var><br> |
| <blockquote> <p>Returns true if the <code>gdb.Frame</code> object is valid, false if not. |
| A frame object can become invalid if the frame it refers to doesn't |
| exist anymore in the inferior. All <code>gdb.Frame</code> methods will throw |
| an exception if it is invalid at the time the method is called. |
| </p></blockquote></div> |
| |
| <div class="defun"> |
| — Method on Frame: <b>name</b><var><a name="index-name-on-Frame-1822"></a></var><br> |
| <blockquote> <p>Returns the function name of the frame, or <code>None</code> if it can't be |
| obtained. |
| </p></blockquote></div> |
| |
| <div class="defun"> |
| — Method on Frame: <b>type</b><var><a name="index-type-on-Frame-1823"></a></var><br> |
| <blockquote> <p>Returns the type of the frame. The value can be one of |
| <code>gdb.NORMAL_FRAME</code>, <code>gdb.DUMMY_FRAME</code>, <code>gdb.SIGTRAMP_FRAME</code> |
| or <code>gdb.SENTINEL_FRAME</code>. |
| </p></blockquote></div> |
| |
| <div class="defun"> |
| — Method on Frame: <b>unwind_stop_reason</b><var><a name="index-unwind_005fstop_005freason-on-Frame-1824"></a></var><br> |
| <blockquote> <p>Return an integer representing the reason why it's not possible to find |
| more frames toward the outermost frame. Use |
| <code>gdb.frame_stop_reason_string</code> to convert the value returned by this |
| function to a string. |
| </p></blockquote></div> |
| |
| <div class="defun"> |
| — Method on Frame: <b>pc</b><var><a name="index-pc-on-Frame-1825"></a></var><br> |
| <blockquote> <p>Returns the frame's resume address. |
| </p></blockquote></div> |
| |
| <div class="defun"> |
| — Method on Frame: <b>block</b><var><a name="index-block-on-Frame-1826"></a></var><br> |
| <blockquote> <p>Return the frame's code block. See <a href="Blocks-In-Python.html#Blocks-In-Python">Blocks In Python</a>. |
| </p></blockquote></div> |
| |
| <div class="defun"> |
| — Method on Frame: <b>function</b><var><a name="index-function-on-Frame-1827"></a></var><br> |
| <blockquote> <p>Return the symbol for the function corresponding to this frame. |
| See <a href="Symbols-In-Python.html#Symbols-In-Python">Symbols In Python</a>. |
| </p></blockquote></div> |
| |
| <div class="defun"> |
| — Method on Frame: <b>older</b><var><a name="index-older-on-Frame-1828"></a></var><br> |
| <blockquote> <p>Return the frame that called this frame. |
| </p></blockquote></div> |
| |
| <div class="defun"> |
| — Method on Frame: <b>newer</b><var><a name="index-newer-on-Frame-1829"></a></var><br> |
| <blockquote> <p>Return the frame called by this frame. |
| </p></blockquote></div> |
| |
| <div class="defun"> |
| — Method on Frame: <b>find_sal</b><var><a name="index-find_005fsal-on-Frame-1830"></a></var><br> |
| <blockquote> <p>Return the frame's symtab and line object. |
| See <a href="Symbol-Tables-In-Python.html#Symbol-Tables-In-Python">Symbol Tables In Python</a>. |
| </p></blockquote></div> |
| |
| <div class="defun"> |
| — Method on Frame: <b>read_var</b><var> variable </var><span class="roman">[</span><var>block</var><span class="roman">]</span><var><a name="index-read_005fvar-on-Frame-1831"></a></var><br> |
| <blockquote> <p>Return the value of <var>variable</var> in this frame. If the optional |
| argument <var>block</var> is provided, search for the variable from that |
| block; otherwise start at the frame's current block (which is |
| determined by the frame's current program counter). <var>variable</var> |
| must be a string or a <code>gdb.Symbol</code> object. <var>block</var> must be a |
| <code>gdb.Block</code> object. |
| </p></blockquote></div> |
| |
| <div class="defun"> |
| — Method on Frame: <b>select</b><var><a name="index-select-on-Frame-1832"></a></var><br> |
| <blockquote> <p>Set this frame to be the selected frame. See <a href="Stack.html#Stack">Examining the Stack</a>. |
| </p></blockquote></div> |
| </dl> |
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