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| Next: <a rel="next" accesskey="n" href="Writing-an-Xmethod.html#Writing-an-Xmethod">Writing an Xmethod</a>, |
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| <h5 class="subsubsection">23.2.2.14 Xmethod API</h5> |
| |
| <p><a name="index-xmethod-API-2040"></a> |
| The <span class="sc">gdb</span> Python API provides classes, interfaces and functions |
| to implement, register and manipulate xmethods. |
| See <a href="Xmethods-In-Python.html#Xmethods-In-Python">Xmethods In Python</a>. |
| |
| <p>An xmethod matcher should be an instance of a class derived from |
| <code>XMethodMatcher</code> defined in the module <code>gdb.xmethod</code>, or an |
| object with similar interface and attributes. An instance of |
| <code>XMethodMatcher</code> has the following attributes: |
| |
| <div class="defun"> |
| — Variable: <b>name</b><var><a name="index-name-2041"></a></var><br> |
| <blockquote><p>The name of the matcher. |
| </p></blockquote></div> |
| |
| <div class="defun"> |
| — Variable: <b>enabled</b><var><a name="index-enabled-2042"></a></var><br> |
| <blockquote><p>A boolean value indicating whether the matcher is enabled or disabled. |
| </p></blockquote></div> |
| |
| <div class="defun"> |
| — Variable: <b>methods</b><var><a name="index-methods-2043"></a></var><br> |
| <blockquote><p>A list of named methods managed by the matcher. Each object in the list |
| is an instance of the class <code>XMethod</code> defined in the module |
| <code>gdb.xmethod</code>, or any object with the following attributes: |
| |
| <dl> |
| <dt><code>name</code><dd>Name of the xmethod which should be unique for each xmethod |
| managed by the matcher. |
| |
| <br><dt><code>enabled</code><dd>A boolean value indicating whether the xmethod is enabled or |
| disabled. |
| |
| </dl> |
| |
| <p>The class <code>XMethod</code> is a convenience class with same |
| attributes as above along with the following constructor: |
| |
| <div class="defun"> |
| — Function: <b>XMethod.__init__</b> (<var>self, name</var>)<var><a name="index-XMethod_002e_005f_005finit_005f_005f-2044"></a></var><br> |
| <blockquote> <p>Constructs an enabled xmethod with name <var>name</var>. |
| </p></blockquote></div> |
| </p></blockquote></div> |
| |
| <p class="noindent">The <code>XMethodMatcher</code> class has the following methods: |
| |
| <div class="defun"> |
| — Function: <b>XMethodMatcher.__init__</b> (<var>self, name</var>)<var><a name="index-XMethodMatcher_002e_005f_005finit_005f_005f-2045"></a></var><br> |
| <blockquote><p>Constructs an enabled xmethod matcher with name <var>name</var>. The |
| <code>methods</code> attribute is initialized to <code>None</code>. |
| </p></blockquote></div> |
| |
| <div class="defun"> |
| — Function: <b>XMethodMatcher.match</b> (<var>self, class_type, method_name</var>)<var><a name="index-XMethodMatcher_002ematch-2046"></a></var><br> |
| <blockquote><p>Derived classes should override this method. It should return a |
| xmethod worker object (or a sequence of xmethod worker |
| objects) matching the <var>class_type</var> and <var>method_name</var>. |
| <var>class_type</var> is a <code>gdb.Type</code> object, and <var>method_name</var> |
| is a string value. If the matcher manages named methods as listed in |
| its <code>methods</code> attribute, then only those worker objects whose |
| corresponding entries in the <code>methods</code> list are enabled should be |
| returned. |
| </p></blockquote></div> |
| |
| <p>An xmethod worker should be an instance of a class derived from |
| <code>XMethodWorker</code> defined in the module <code>gdb.xmethod</code>, |
| or support the following interface: |
| |
| <div class="defun"> |
| — Function: <b>XMethodWorker.get_arg_types</b> (<var>self</var>)<var><a name="index-XMethodWorker_002eget_005farg_005ftypes-2047"></a></var><br> |
| <blockquote><p>This method returns a sequence of <code>gdb.Type</code> objects corresponding |
| to the arguments that the xmethod takes. It can return an empty |
| sequence or <code>None</code> if the xmethod does not take any arguments. |
| If the xmethod takes a single argument, then a single |
| <code>gdb.Type</code> object corresponding to it can be returned. |
| </p></blockquote></div> |
| |
| <div class="defun"> |
| — Function: <b>XMethodWorker.get_result_type</b> (<var>self, *args</var>)<var><a name="index-XMethodWorker_002eget_005fresult_005ftype-2048"></a></var><br> |
| <blockquote><p>This method returns a <code>gdb.Type</code> object representing the type |
| of the result of invoking this xmethod. |
| The <var>args</var> argument is the same tuple of arguments that would be |
| passed to the <code>__call__</code> method of this worker. |
| </p></blockquote></div> |
| |
| <div class="defun"> |
| — Function: <b>XMethodWorker.__call__</b> (<var>self, *args</var>)<var><a name="index-XMethodWorker_002e_005f_005fcall_005f_005f-2049"></a></var><br> |
| <blockquote><p>This is the method which does the <em>work</em> of the xmethod. The |
| <var>args</var> arguments is the tuple of arguments to the xmethod. Each |
| element in this tuple is a gdb.Value object. The first element is |
| always the <code>this</code> pointer value. |
| </p></blockquote></div> |
| |
| <p>For <span class="sc">gdb</span> to lookup xmethods, the xmethod matchers |
| should be registered using the following function defined in the module |
| <code>gdb.xmethod</code>: |
| |
| <div class="defun"> |
| — Function: <b>register_xmethod_matcher</b> (<var>locus, matcher, replace=False</var>)<var><a name="index-register_005fxmethod_005fmatcher-2050"></a></var><br> |
| <blockquote><p>The <code>matcher</code> is registered with <code>locus</code>, replacing an |
| existing matcher with the same name as <code>matcher</code> if |
| <code>replace</code> is <code>True</code>. <code>locus</code> can be a |
| <code>gdb.Objfile</code> object (see <a href="Objfiles-In-Python.html#Objfiles-In-Python">Objfiles In Python</a>), or a |
| <code>gdb.Progspace</code> object (see <a href="Progspaces-In-Python.html#Progspaces-In-Python">Progspaces In Python</a>), or |
| <code>None</code>. If it is <code>None</code>, then <code>matcher</code> is registered |
| globally. |
| </p></blockquote></div> |
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