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| <a name="Commands-In-Python"></a> |
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| |
| <h5 class="subsubsection">23.2.2.10 Commands In Python</h5> |
| |
| <p><a name="index-commands-in-python-1723"></a><a name="index-python-commands-1724"></a>You can implement new <span class="sc">gdb</span> CLI commands in Python. A CLI |
| command is implemented using an instance of the <code>gdb.Command</code> |
| class, most commonly using a subclass. |
| |
| <div class="defun"> |
| — Method on Command: <b>__init__</b><var> name command_class </var><span class="roman">[</span><var>completer_class</var><span class="roman">]</span> <span class="roman">[</span><var>prefix</var><span class="roman">]</span><var><a name="index-g_t_005f_005finit_005f_005f-on-Command-1725"></a></var><br> |
| <blockquote><p>The object initializer for <code>Command</code> registers the new command |
| with <span class="sc">gdb</span>. This initializer is normally invoked from the |
| subclass' own <code>__init__</code> method. |
| |
| <p><var>name</var> is the name of the command. If <var>name</var> consists of |
| multiple words, then the initial words are looked for as prefix |
| commands. In this case, if one of the prefix commands does not exist, |
| an exception is raised. |
| |
| <p>There is no support for multi-line commands. |
| |
| <p><var>command_class</var> should be one of the ‘<samp><span class="samp">COMMAND_</span></samp>’ constants |
| defined below. This argument tells <span class="sc">gdb</span> how to categorize the |
| new command in the help system. |
| |
| <p><var>completer_class</var> is an optional argument. If given, it should be |
| one of the ‘<samp><span class="samp">COMPLETE_</span></samp>’ constants defined below. This argument |
| tells <span class="sc">gdb</span> how to perform completion for this command. If not |
| given, <span class="sc">gdb</span> will attempt to complete using the object's |
| <code>complete</code> method (see below); if no such method is found, an |
| error will occur when completion is attempted. |
| |
| <p><var>prefix</var> is an optional argument. If <code>True</code>, then the new |
| command is a prefix command; sub-commands of this command may be |
| registered. |
| |
| <p>The help text for the new command is taken from the Python |
| documentation string for the command's class, if there is one. If no |
| documentation string is provided, the default value “This command is |
| not documented.” is used. |
| </p></blockquote></div> |
| |
| <p><a name="index-don_0027t-repeat-Python-command-1726"></a> |
| |
| <div class="defun"> |
| — Method on Command: <b>dont_repeat</b><var><a name="index-dont_005frepeat-on-Command-1727"></a></var><br> |
| <blockquote><p>By default, a <span class="sc">gdb</span> command is repeated when the user enters a |
| blank line at the command prompt. A command can suppress this |
| behavior by invoking the <code>dont_repeat</code> method. This is similar |
| to the user command <code>dont-repeat</code>, see <a href="Define.html#Define">dont-repeat</a>. |
| </p></blockquote></div> |
| |
| <div class="defun"> |
| — Method on Command: <b>invoke</b><var> argument from_tty<a name="index-invoke-on-Command-1728"></a></var><br> |
| <blockquote><p>This method is called by <span class="sc">gdb</span> when this command is invoked. |
| |
| <p><var>argument</var> is a string. It is the argument to the command, after |
| leading and trailing whitespace has been stripped. |
| |
| <p><var>from_tty</var> is a boolean argument. When true, this means that the |
| command was entered by the user at the terminal; when false it means |
| that the command came from elsewhere. |
| |
| <p>If this method throws an exception, it is turned into a <span class="sc">gdb</span> |
| <code>error</code> call. Otherwise, the return value is ignored. |
| |
| <p><a name="index-gdb_002estring_005fto_005fargv-1729"></a>To break <var>argument</var> up into an argv-like string use |
| <code>gdb.string_to_argv</code>. This function behaves identically to |
| <span class="sc">gdb</span>'s internal argument lexer <code>buildargv</code>. |
| It is recommended to use this for consistency. |
| Arguments are separated by spaces and may be quoted. |
| Example: |
| |
| <pre class="smallexample"> print gdb.string_to_argv ("1 2\ \\\"3 '4 \"5' \"6 '7\"") |
| ['1', '2 "3', '4 "5', "6 '7"] |
| </pre> |
| </blockquote></div> |
| |
| <p><a name="index-completion-of-Python-commands-1730"></a> |
| |
| <div class="defun"> |
| — Method on Command: <b>complete</b><var> text word<a name="index-complete-on-Command-1731"></a></var><br> |
| <blockquote><p>This method is called by <span class="sc">gdb</span> when the user attempts |
| completion on this command. All forms of completion are handled by |
| this method, that is, the <TAB> and <M-?> key bindings |
| (see <a href="Completion.html#Completion">Completion</a>), and the <code>complete</code> command (see <a href="Help.html#Help">complete</a>). |
| |
| <p>The arguments <var>text</var> and <var>word</var> are both strings. <var>text</var> |
| holds the complete command line up to the cursor's location. |
| <var>word</var> holds the last word of the command line; this is computed |
| using a word-breaking heuristic. |
| |
| <p>The <code>complete</code> method can return several values: |
| <ul> |
| <li>If the return value is a sequence, the contents of the sequence are |
| used as the completions. It is up to <code>complete</code> to ensure that the |
| contents actually do complete the word. A zero-length sequence is |
| allowed, it means that there were no completions available. Only |
| string elements of the sequence are used; other elements in the |
| sequence are ignored. |
| |
| <li>If the return value is one of the ‘<samp><span class="samp">COMPLETE_</span></samp>’ constants defined |
| below, then the corresponding <span class="sc">gdb</span>-internal completion |
| function is invoked, and its result is used. |
| |
| <li>All other results are treated as though there were no available |
| completions. |
| </ul> |
| </p></blockquote></div> |
| |
| <p>When a new command is registered, it must be declared as a member of |
| some general class of commands. This is used to classify top-level |
| commands in the on-line help system; note that prefix commands are not |
| listed under their own category but rather that of their top-level |
| command. The available classifications are represented by constants |
| defined in the <code>gdb</code> module: |
| |
| |
| <a name="index-COMMAND_005fNONE-1732"></a> |
| <a name="index-gdb_002eCOMMAND_005fNONE-1733"></a> |
| <dl><dt><code>COMMAND_NONE</code><dd>The command does not belong to any particular class. A command in |
| this category will not be displayed in any of the help categories. |
| |
| <p><a name="index-COMMAND_005fRUNNING-1734"></a><a name="index-gdb_002eCOMMAND_005fRUNNING-1735"></a><br><dt><code>COMMAND_RUNNING</code><dd>The command is related to running the inferior. For example, |
| <code>start</code>, <code>step</code>, and <code>continue</code> are in this category. |
| Type <kbd>help running</kbd> at the <span class="sc">gdb</span> prompt to see a list of |
| commands in this category. |
| |
| <p><a name="index-COMMAND_005fDATA-1736"></a><a name="index-gdb_002eCOMMAND_005fDATA-1737"></a><br><dt><code>COMMAND_DATA</code><dd>The command is related to data or variables. For example, |
| <code>call</code>, <code>find</code>, and <code>print</code> are in this category. Type |
| <kbd>help data</kbd> at the <span class="sc">gdb</span> prompt to see a list of commands |
| in this category. |
| |
| <p><a name="index-COMMAND_005fSTACK-1738"></a><a name="index-gdb_002eCOMMAND_005fSTACK-1739"></a><br><dt><code>COMMAND_STACK</code><dd>The command has to do with manipulation of the stack. For example, |
| <code>backtrace</code>, <code>frame</code>, and <code>return</code> are in this |
| category. Type <kbd>help stack</kbd> at the <span class="sc">gdb</span> prompt to see a |
| list of commands in this category. |
| |
| <p><a name="index-COMMAND_005fFILES-1740"></a><a name="index-gdb_002eCOMMAND_005fFILES-1741"></a><br><dt><code>COMMAND_FILES</code><dd>This class is used for file-related commands. For example, |
| <code>file</code>, <code>list</code> and <code>section</code> are in this category. |
| Type <kbd>help files</kbd> at the <span class="sc">gdb</span> prompt to see a list of |
| commands in this category. |
| |
| <p><a name="index-COMMAND_005fSUPPORT-1742"></a><a name="index-gdb_002eCOMMAND_005fSUPPORT-1743"></a><br><dt><code>COMMAND_SUPPORT</code><dd>This should be used for “support facilities”, generally meaning |
| things that are useful to the user when interacting with <span class="sc">gdb</span>, |
| but not related to the state of the inferior. For example, |
| <code>help</code>, <code>make</code>, and <code>shell</code> are in this category. Type |
| <kbd>help support</kbd> at the <span class="sc">gdb</span> prompt to see a list of |
| commands in this category. |
| |
| <p><a name="index-COMMAND_005fSTATUS-1744"></a><a name="index-gdb_002eCOMMAND_005fSTATUS-1745"></a><br><dt><code>COMMAND_STATUS</code><dd>The command is an ‘<samp><span class="samp">info</span></samp>’-related command, that is, related to the |
| state of <span class="sc">gdb</span> itself. For example, <code>info</code>, <code>macro</code>, |
| and <code>show</code> are in this category. Type <kbd>help status</kbd> at the |
| <span class="sc">gdb</span> prompt to see a list of commands in this category. |
| |
| <p><a name="index-COMMAND_005fBREAKPOINTS-1746"></a><a name="index-gdb_002eCOMMAND_005fBREAKPOINTS-1747"></a><br><dt><code>COMMAND_BREAKPOINTS</code><dd>The command has to do with breakpoints. For example, <code>break</code>, |
| <code>clear</code>, and <code>delete</code> are in this category. Type <kbd>help |
| breakpoints</kbd> at the <span class="sc">gdb</span> prompt to see a list of commands in |
| this category. |
| |
| <p><a name="index-COMMAND_005fTRACEPOINTS-1748"></a><a name="index-gdb_002eCOMMAND_005fTRACEPOINTS-1749"></a><br><dt><code>COMMAND_TRACEPOINTS</code><dd>The command has to do with tracepoints. For example, <code>trace</code>, |
| <code>actions</code>, and <code>tfind</code> are in this category. Type |
| <kbd>help tracepoints</kbd> at the <span class="sc">gdb</span> prompt to see a list of |
| commands in this category. |
| |
| <p><a name="index-COMMAND_005fOBSCURE-1750"></a><a name="index-gdb_002eCOMMAND_005fOBSCURE-1751"></a><br><dt><code>COMMAND_OBSCURE</code><dd>The command is only used in unusual circumstances, or is not of |
| general interest to users. For example, <code>checkpoint</code>, |
| <code>fork</code>, and <code>stop</code> are in this category. Type <kbd>help |
| obscure</kbd> at the <span class="sc">gdb</span> prompt to see a list of commands in this |
| category. |
| |
| <p><a name="index-COMMAND_005fMAINTENANCE-1752"></a><a name="index-gdb_002eCOMMAND_005fMAINTENANCE-1753"></a><br><dt><code>COMMAND_MAINTENANCE</code><dd>The command is only useful to <span class="sc">gdb</span> maintainers. The |
| <code>maintenance</code> and <code>flushregs</code> commands are in this category. |
| Type <kbd>help internals</kbd> at the <span class="sc">gdb</span> prompt to see a list of |
| commands in this category. |
| </dl> |
| |
| <p>A new command can use a predefined completion function, either by |
| specifying it via an argument at initialization, or by returning it |
| from the <code>complete</code> method. These predefined completion |
| constants are all defined in the <code>gdb</code> module: |
| |
| |
| <a name="index-COMPLETE_005fNONE-1754"></a> |
| <a name="index-gdb_002eCOMPLETE_005fNONE-1755"></a> |
| <dl><dt><code>COMPLETE_NONE</code><dd>This constant means that no completion should be done. |
| |
| <p><a name="index-COMPLETE_005fFILENAME-1756"></a><a name="index-gdb_002eCOMPLETE_005fFILENAME-1757"></a><br><dt><code>COMPLETE_FILENAME</code><dd>This constant means that filename completion should be performed. |
| |
| <p><a name="index-COMPLETE_005fLOCATION-1758"></a><a name="index-gdb_002eCOMPLETE_005fLOCATION-1759"></a><br><dt><code>COMPLETE_LOCATION</code><dd>This constant means that location completion should be done. |
| See <a href="Specify-Location.html#Specify-Location">Specify Location</a>. |
| |
| <p><a name="index-COMPLETE_005fCOMMAND-1760"></a><a name="index-gdb_002eCOMPLETE_005fCOMMAND-1761"></a><br><dt><code>COMPLETE_COMMAND</code><dd>This constant means that completion should examine <span class="sc">gdb</span> |
| command names. |
| |
| <p><a name="index-COMPLETE_005fSYMBOL-1762"></a><a name="index-gdb_002eCOMPLETE_005fSYMBOL-1763"></a><br><dt><code>COMPLETE_SYMBOL</code><dd>This constant means that completion should be done using symbol names |
| as the source. |
| </dl> |
| |
| <p>The following code snippet shows how a trivial CLI command can be |
| implemented in Python: |
| |
| <pre class="smallexample"> class HelloWorld (gdb.Command): |
| """Greet the whole world.""" |
| |
| def __init__ (self): |
| super (HelloWorld, self).__init__ ("hello-world", gdb.COMMAND_OBSCURE) |
| |
| def invoke (self, arg, from_tty): |
| print "Hello, World!" |
| |
| HelloWorld () |
| </pre> |
| <p>The last line instantiates the class, and is necessary to trigger the |
| registration of the command with <span class="sc">gdb</span>. Depending on how the |
| Python code is read into <span class="sc">gdb</span>, you may need to import the |
| <code>gdb</code> module explicitly. |
| |
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