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GeezerVison is showing github.com — python-doc-tw.github.io/library/cmd.html at master · python-doc-tw/python-doc-tw.github.io Expand file tree/ Copy pathcmd.htmlMore file actions 544 lines (489 loc) · 43.1 KB / Copy pathcmd.htmlFile metadata and controls544 lines (489 loc) · 43.1 KB 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" lang="zh_TW"> <head> <meta http-equiv="X-UA-Compatible" content="IE=Edge" /> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <title>25.2. cmd — Support for line-oriented command interpreters — Python 3.7.0 說明文件</title> <link rel="stylesheet" href="../_static/pydoctheme.css" type="text/css" /> <link rel="stylesheet" href="../_static/pygments.css" type="text/css" /> <script type="text/javascript" id="documentation_options" data-url_root="../" src="../_static/documentation_options.js"></script> <script type="text/javascript" src="../_static/jquery.js"></script> <script type="text/javascript" src="../_static/underscore.js"></script> <script type="text/javascript" src="../_static/doctools.js"></script> <script type="text/javascript" src="../_static/translations.js"></script> <script type="text/javascript" src="../_static/sidebar.js"></script> <link rel="search" type="application/opensearchdescription+xml" title="在 Python 3.7.0 說明文件 中搜尋" href="../_static/opensearch.xml"/> <link rel="author" title="關於這些文件" href="../about.html" /> <link rel="index" title="索引" href="../genindex.html" /> <link rel="search" title="搜尋" href="../search.html" /> <link rel="copyright" title="Copyright" href="../copyright.html" /> <link rel="next" title="25.3. shlex — Simple lexical analysis" href="shlex.html" /> <link rel="prev" title="25.1. turtle — 龜圖學" href="turtle.html" /> <link rel="shortcut icon" type="image/png" href="../_static/py.png" /> <link rel="canonical" href="https://docs.python.org/3/library/cmd.html" /> <script type="text/javascript" src="../_static/copybutton.js"></script> <script type="text/javascript" src="../_static/switchers.js"></script> </head><body> <div class="related" role="navigation" aria-label="related navigation"> <h3>瀏覽</h3> <ul> <li class="right" style="margin-right: 10px"> <a href="../genindex.html" title="General Index" accesskey="I">索引</a></li> <li class="right" > <a href="../py-modindex.html" title="Python 模組索引" >模組</a> |</li> <li class="right" > <a href="shlex.html" title="25.3. shlex — Simple lexical analysis" accesskey="N">下一頁</a> |</li> <li class="right" > <a href="turtle.html" title="25.1. turtle — 龜圖學" accesskey="P">上一頁</a> |</li> <li><img src="../_static/py.png" alt="" style="vertical-align: middle; margin-top: -1px"/></li> <li><a href="https://www.python.org/">Python</a> »</li> <li> <span class="language_switcher_placeholder">zh_TW</span> <span class="version_switcher_placeholder">3.7.0</span> <a href="../index.html">Documentation </a> » </li> <li class="nav-item nav-item-1"><a href="index.html" >Python 標準函式庫 (Standard Library)</a> »</li> <li class="nav-item nav-item-2"><a href="frameworks.html" accesskey="U">25. 程式框架</a> »</li> <li class="right"> <div class="inline-search" style="display: none" role="search"> <form class="inline-search" action="../search.html" method="get"> <input placeholder="Quick search" type="text" name="q" /> <input type="submit" value="Go" /> <input type="hidden" name="check_keywords" value="yes" /> <input type="hidden" name="area" value="default" /> </form> </div> <script type="text/javascript">$('.inline-search').show(0);</script> | </li> </ul> </div> <div class="document"> <div class="documentwrapper"> <div class="bodywrapper"> <div class="body" role="main"> <div class="section" id="module-cmd"> <span id="cmd-support-for-line-oriented-command-interpreters"></span><h1>25.2. <a class="reference internal" href="#module-cmd" title="cmd: Build line-oriented command interpreters."><code class="xref py py-mod docutils literal notranslate"><span class="pre">cmd</span></code></a> — Support for line-oriented command interpreters<a class="headerlink" href="#module-cmd" title="本標題的永久連結">¶</a></h1> <p><strong>Source code:</strong> <a class="reference external" href="https://github.com/python/cpython/tree/3.7/Lib/cmd.py">Lib/cmd.py</a></p> <hr class="docutils" /> <p>The <a class="reference internal" href="#cmd.Cmd" title="cmd.Cmd"><code class="xref py py-class docutils literal notranslate"><span class="pre">Cmd</span></code></a> class provides a simple framework for writing line-oriented command interpreters. These are often useful for test harnesses, administrative tools, and prototypes that will later be wrapped in a more sophisticated interface.</p> <dl class="class"> <dt id="cmd.Cmd"> <em class="property">class </em><code class="descclassname">cmd.</code><code class="descname">Cmd</code><span class="sig-paren">(</span><em>completekey='tab'</em>, <em>stdin=None</em>, <em>stdout=None</em><span class="sig-paren">)</span><a class="headerlink" href="#cmd.Cmd" title="本定義的永久連結">¶</a></dt> <dd><p>A <a class="reference internal" href="#cmd.Cmd" title="cmd.Cmd"><code class="xref py py-class docutils literal notranslate"><span class="pre">Cmd</span></code></a> instance or subclass instance is a line-oriented interpreter framework. There is no good reason to instantiate <a class="reference internal" href="#cmd.Cmd" title="cmd.Cmd"><code class="xref py py-class docutils literal notranslate"><span class="pre">Cmd</span></code></a> itself; rather, it’s useful as a superclass of an interpreter class you define yourself in order to inherit <a class="reference internal" href="#cmd.Cmd" title="cmd.Cmd"><code class="xref py py-class docutils literal notranslate"><span class="pre">Cmd</span></code></a>’s methods and encapsulate action methods.</p> <p>The optional argument <em>completekey</em> is the <a class="reference internal" href="readline.html#module-readline" title="readline: GNU readline support for Python. (Unix)"><code class="xref py py-mod docutils literal notranslate"><span class="pre">readline</span></code></a> name of a completion key; it defaults to <kbd class="kbd docutils literal notranslate">Tab</kbd>. If <em>completekey</em> is not <a class="reference internal" href="constants.html#None" title="None"><code class="xref py py-const docutils literal notranslate"><span class="pre">None</span></code></a> and <a class="reference internal" href="readline.html#module-readline" title="readline: GNU readline support for Python. (Unix)"><code class="xref py py-mod docutils literal notranslate"><span class="pre">readline</span></code></a> is available, command completion is done automatically.</p> <p>The optional arguments <em>stdin</em> and <em>stdout</em> specify the input and output file objects that the Cmd instance or subclass instance will use for input and output. If not specified, they will default to <a class="reference internal" href="sys.html#sys.stdin" title="sys.stdin"><code class="xref py py-data docutils literal notranslate"><span class="pre">sys.stdin</span></code></a> and <a class="reference internal" href="sys.html#sys.stdout" title="sys.stdout"><code class="xref py py-data docutils literal notranslate"><span class="pre">sys.stdout</span></code></a>.</p> <p>If you want a given <em>stdin</em> to be used, make sure to set the instance’s <a class="reference internal" href="#cmd.Cmd.use_rawinput" title="cmd.Cmd.use_rawinput"><code class="xref py py-attr docutils literal notranslate"><span class="pre">use_rawinput</span></code></a> attribute to <code class="docutils literal notranslate"><span class="pre">False</span></code>, otherwise <em>stdin</em> will be ignored.</p> </dd></dl> <div class="section" id="cmd-objects"> <span id="id1"></span><h2>25.2.1. Cmd Objects<a class="headerlink" href="#cmd-objects" title="本標題的永久連結">¶</a></h2> <p>A <a class="reference internal" href="#cmd.Cmd" title="cmd.Cmd"><code class="xref py py-class docutils literal notranslate"><span class="pre">Cmd</span></code></a> instance has the following methods:</p> <dl class="method"> <dt id="cmd.Cmd.cmdloop"> <code class="descclassname">Cmd.</code><code class="descname">cmdloop</code><span class="sig-paren">(</span><em>intro=None</em><span class="sig-paren">)</span><a class="headerlink" href="#cmd.Cmd.cmdloop" title="本定義的永久連結">¶</a></dt> <dd><p>Repeatedly issue a prompt, accept input, parse an initial prefix off the received input, and dispatch to action methods, passing them the remainder of the line as argument.</p> <p>The optional argument is a banner or intro string to be issued before the first prompt (this overrides the <a class="reference internal" href="#cmd.Cmd.intro" title="cmd.Cmd.intro"><code class="xref py py-attr docutils literal notranslate"><span class="pre">intro</span></code></a> class attribute).</p> <p>If the <a class="reference internal" href="readline.html#module-readline" title="readline: GNU readline support for Python. (Unix)"><code class="xref py py-mod docutils literal notranslate"><span class="pre">readline</span></code></a> module is loaded, input will automatically inherit <strong class="program">bash</strong>-like history-list editing (e.g. <kbd class="kbd docutils literal notranslate">Control-P</kbd> scrolls back to the last command, <kbd class="kbd docutils literal notranslate">Control-N</kbd> forward to the next one, <kbd class="kbd docutils literal notranslate">Control-F</kbd> moves the cursor to the right non-destructively, <kbd class="kbd docutils literal notranslate">Control-B</kbd> moves the cursor to the left non-destructively, etc.).</p> <p>An end-of-file on input is passed back as the string <code class="docutils literal notranslate"><span class="pre">'EOF'</span></code>.</p> <p>An interpreter instance will recognize a command name <code class="docutils literal notranslate"><span class="pre">foo</span></code> if and only if it has a method <code class="xref py py-meth docutils literal notranslate"><span class="pre">do_foo()</span></code>. As a special case, a line beginning with the character <code class="docutils literal notranslate"><span class="pre">'?'</span></code> is dispatched to the method <code class="xref py py-meth docutils literal notranslate"><span class="pre">do_help()</span></code>. As another special case, a line beginning with the character <code class="docutils literal notranslate"><span class="pre">'!'</span></code> is dispatched to the method <code class="xref py py-meth docutils literal notranslate"><span class="pre">do_shell()</span></code> (if such a method is defined).</p> <p>This method will return when the <a class="reference internal" href="#cmd.Cmd.postcmd" title="cmd.Cmd.postcmd"><code class="xref py py-meth docutils literal notranslate"><span class="pre">postcmd()</span></code></a> method returns a true value. The <em>stop</em> argument to <a class="reference internal" href="#cmd.Cmd.postcmd" title="cmd.Cmd.postcmd"><code class="xref py py-meth docutils literal notranslate"><span class="pre">postcmd()</span></code></a> is the return value from the command’s corresponding <code class="xref py py-meth docutils literal notranslate"><span class="pre">do_*()</span></code> method.</p> <p>If completion is enabled, completing commands will be done automatically, and completing of commands args is done by calling <code class="xref py py-meth docutils literal notranslate"><span class="pre">complete_foo()</span></code> with arguments <em>text</em>, <em>line</em>, <em>begidx</em>, and <em>endidx</em>. <em>text</em> is the string prefix we are attempting to match: all returned matches must begin with it. <em>line</em> is the current input line with leading whitespace removed, <em>begidx</em> and <em>endidx</em> are the beginning and ending indexes of the prefix text, which could be used to provide different completion depending upon which position the argument is in.</p> <p>All subclasses of <a class="reference internal" href="#cmd.Cmd" title="cmd.Cmd"><code class="xref py py-class docutils literal notranslate"><span class="pre">Cmd</span></code></a> inherit a predefined <code class="xref py py-meth docutils literal notranslate"><span class="pre">do_help()</span></code>. This method, called with an argument <code class="docutils literal notranslate"><span class="pre">'bar'</span></code>, invokes the corresponding method <code class="xref py py-meth docutils literal notranslate"><span class="pre">help_bar()</span></code>, and if that is not present, prints the docstring of <code class="xref py py-meth docutils literal notranslate"><span class="pre">do_bar()</span></code>, if available. With no argument, <code class="xref py py-meth docutils literal notranslate"><span class="pre">do_help()</span></code> lists all available help topics (that is, all commands with corresponding <code class="xref py py-meth docutils literal notranslate"><span class="pre">help_*()</span></code> methods or commands that have docstrings), and also lists any undocumented commands.</p> </dd></dl> <dl class="method"> <dt id="cmd.Cmd.onecmd"> <code class="descclassname">Cmd.</code><code class="descname">onecmd</code><span class="sig-paren">(</span><em>str</em><span class="sig-paren">)</span><a class="headerlink" href="#cmd.Cmd.onecmd" title="本定義的永久連結">¶</a></dt> <dd><p>Interpret the argument as though it had been typed in response to the prompt. This may be overridden, but should not normally need to be; see the <a class="reference internal" href="#cmd.Cmd.precmd" title="cmd.Cmd.precmd"><code class="xref py py-meth docutils literal notranslate"><span class="pre">precmd()</span></code></a> and <a class="reference internal" href="#cmd.Cmd.postcmd" title="cmd.Cmd.postcmd"><code class="xref py py-meth docutils literal notranslate"><span class="pre">postcmd()</span></code></a> methods for useful execution hooks. The return value is a flag indicating whether interpretation of commands by the interpreter should stop. If there is a <code class="xref py py-meth docutils literal notranslate"><span class="pre">do_*()</span></code> method for the command <em>str</em>, the return value of that method is returned, otherwise the return value from the <a class="reference internal" href="#cmd.Cmd.default" title="cmd.Cmd.default"><code class="xref py py-meth docutils literal notranslate"><span class="pre">default()</span></code></a> method is returned.</p> </dd></dl> <dl class="method"> <dt id="cmd.Cmd.emptyline"> <code class="descclassname">Cmd.</code><code class="descname">emptyline</code><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#cmd.Cmd.emptyline" title="本定義的永久連結">¶</a></dt> <dd><p>Method called when an empty line is entered in response to the prompt. If this method is not overridden, it repeats the last nonempty command entered.</p> </dd></dl> <dl class="method"> <dt id="cmd.Cmd.default"> <code class="descclassname">Cmd.</code><code class="descname">default</code><span class="sig-paren">(</span><em>line</em><span class="sig-paren">)</span><a class="headerlink" href="#cmd.Cmd.default" title="本定義的永久連結">¶</a></dt> <dd><p>Method called on an input line when the command prefix is not recognized. If this method is not overridden, it prints an error message and returns.</p> </dd></dl> <dl class="method"> <dt id="cmd.Cmd.completedefault"> <code class="descclassname">Cmd.</code><code class="descname">completedefault</code><span class="sig-paren">(</span><em>text</em>, <em>line</em>, <em>begidx</em>, <em>endidx</em><span class="sig-paren">)</span><a class="headerlink" href="#cmd.Cmd.completedefault" title="本定義的永久連結">¶</a></dt> <dd><p>Method called to complete an input line when no command-specific <code class="xref py py-meth docutils literal notranslate"><span class="pre">complete_*()</span></code> method is available. By default, it returns an empty list.</p> </dd></dl> <dl class="method"> <dt id="cmd.Cmd.precmd"> <code class="descclassname">Cmd.</code><code class="descname">precmd</code><span class="sig-paren">(</span><em>line</em><span class="sig-paren">)</span><a class="headerlink" href="#cmd.Cmd.precmd" title="本定義的永久連結">¶</a></dt> <dd><p>Hook method executed just before the command line <em>line</em> is interpreted, but after the input prompt is generated and issued. This method is a stub in <a class="reference internal" href="#cmd.Cmd" title="cmd.Cmd"><code class="xref py py-class docutils literal notranslate"><span class="pre">Cmd</span></code></a>; it exists to be overridden by subclasses. The return value is used as the command which will be executed by the <a class="reference internal" href="#cmd.Cmd.onecmd" title="cmd.Cmd.onecmd"><code class="xref py py-meth docutils literal notranslate"><span class="pre">onecmd()</span></code></a> method; the <a class="reference internal" href="#cmd.Cmd.precmd" title="cmd.Cmd.precmd"><code class="xref py py-meth docutils literal notranslate"><span class="pre">precmd()</span></code></a> implementation may re-write the command or simply return <em>line</em> unchanged.</p> </dd></dl> <dl class="method"> <dt id="cmd.Cmd.postcmd"> <code class="descclassname">Cmd.</code><code class="descname">postcmd</code><span class="sig-paren">(</span><em>stop</em>, <em>line</em><span class="sig-paren">)</span><a class="headerlink" href="#cmd.Cmd.postcmd" title="本定義的永久連結">¶</a></dt> <dd><p>Hook method executed just after a command dispatch is finished. This method is a stub in <a class="reference internal" href="#cmd.Cmd" title="cmd.Cmd"><code class="xref py py-class docutils literal notranslate"><span class="pre">Cmd</span></code></a>; it exists to be overridden by subclasses. <em>line</em> is the command line which was executed, and <em>stop</em> is a flag which indicates whether execution will be terminated after the call to <a class="reference internal" href="#cmd.Cmd.postcmd" title="cmd.Cmd.postcmd"><code class="xref py py-meth docutils literal notranslate"><span class="pre">postcmd()</span></code></a>; this will be the return value of the <a class="reference internal" href="#cmd.Cmd.onecmd" title="cmd.Cmd.onecmd"><code class="xref py py-meth docutils literal notranslate"><span class="pre">onecmd()</span></code></a> method. The return value of this method will be used as the new value for the internal flag which corresponds to <em>stop</em>; returning false will cause interpretation to continue.</p> </dd></dl> <dl class="method"> <dt id="cmd.Cmd.preloop"> <code class="descclassname">Cmd.</code><code class="descname">preloop</code><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#cmd.Cmd.preloop" title="本定義的永久連結">¶</a></dt> <dd><p>Hook method executed once when <a class="reference internal" href="#cmd.Cmd.cmdloop" title="cmd.Cmd.cmdloop"><code class="xref py py-meth docutils literal notranslate"><span class="pre">cmdloop()</span></code></a> is called. This method is a stub in <a class="reference internal" href="#cmd.Cmd" title="cmd.Cmd"><code class="xref py py-class docutils literal notranslate"><span class="pre">Cmd</span></code></a>; it exists to be overridden by subclasses.</p> </dd></dl> <dl class="method"> <dt id="cmd.Cmd.postloop"> <code class="descclassname">Cmd.</code><code class="descname">postloop</code><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#cmd.Cmd.postloop" title="本定義的永久連結">¶</a></dt> <dd><p>Hook method executed once when <a class="reference internal" href="#cmd.Cmd.cmdloop" title="cmd.Cmd.cmdloop"><code class="xref py py-meth docutils literal notranslate"><span class="pre">cmdloop()</span></code></a> is about to return. This method is a stub in <a class="reference internal" href="#cmd.Cmd" title="cmd.Cmd"><code class="xref py py-class docutils literal notranslate"><span class="pre">Cmd</span></code></a>; it exists to be overridden by subclasses.</p> </dd></dl> <p>Instances of <a class="reference internal" href="#cmd.Cmd" title="cmd.Cmd"><code class="xref py py-class docutils literal notranslate"><span class="pre">Cmd</span></code></a> subclasses have some public instance variables:</p> <dl class="attribute"> <dt id="cmd.Cmd.prompt"> <code class="descclassname">Cmd.</code><code class="descname">prompt</code><a class="headerlink" href="#cmd.Cmd.prompt" title="本定義的永久連結">¶</a></dt> <dd><p>The prompt issued to solicit input.</p> </dd></dl> <dl class="attribute"> <dt id="cmd.Cmd.identchars"> <code class="descclassname">Cmd.</code><code class="descname">identchars</code><a class="headerlink" href="#cmd.Cmd.identchars" title="本定義的永久連結">¶</a></dt> <dd><p>The string of characters accepted for the command prefix.</p> </dd></dl> <dl class="attribute"> <dt id="cmd.Cmd.lastcmd"> <code class="descclassname">Cmd.</code><code class="descname">lastcmd</code><a class="headerlink" href="#cmd.Cmd.lastcmd" title="本定義的永久連結">¶</a></dt> <dd><p>The last nonempty command prefix seen.</p> </dd></dl> <dl class="attribute"> <dt id="cmd.Cmd.cmdqueue"> <code class="descclassname">Cmd.</code><code class="descname">cmdqueue</code><a class="headerlink" href="#cmd.Cmd.cmdqueue" title="本定義的永久連結">¶</a></dt> <dd><p>A list of queued input lines. The cmdqueue list is checked in <a class="reference internal" href="#cmd.Cmd.cmdloop" title="cmd.Cmd.cmdloop"><code class="xref py py-meth docutils literal notranslate"><span class="pre">cmdloop()</span></code></a> when new input is needed; if it is nonempty, its elements will be processed in order, as if entered at the prompt.</p> </dd></dl> <dl class="attribute"> <dt id="cmd.Cmd.intro"> <code class="descclassname">Cmd.</code><code class="descname">intro</code><a class="headerlink" href="#cmd.Cmd.intro" title="本定義的永久連結">¶</a></dt> <dd><p>A string to issue as an intro or banner. May be overridden by giving the <a class="reference internal" href="#cmd.Cmd.cmdloop" title="cmd.Cmd.cmdloop"><code class="xref py py-meth docutils literal notranslate"><span class="pre">cmdloop()</span></code></a> method an argument.</p> </dd></dl> <dl class="attribute"> <dt id="cmd.Cmd.doc_header"> <code class="descclassname">Cmd.</code><code class="descname">doc_header</code><a class="headerlink" href="#cmd.Cmd.doc_header" title="本定義的永久連結">¶</a></dt> <dd><p>The header to issue if the help output has a section for documented commands.</p> </dd></dl> <dl class="attribute"> <dt id="cmd.Cmd.misc_header"> <code class="descclassname">Cmd.</code><code class="descname">misc_header</code><a class="headerlink" href="#cmd.Cmd.misc_header" title="本定義的永久連結">¶</a></dt> <dd><p>The header to issue if the help output has a section for miscellaneous help topics (that is, there are <code class="xref py py-meth docutils literal notranslate"><span class="pre">help_*()</span></code> methods without corresponding <code class="xref py py-meth docutils literal notranslate"><span class="pre">do_*()</span></code> methods).</p> </dd></dl> <dl class="attribute"> <dt id="cmd.Cmd.undoc_header"> <code class="descclassname">Cmd.</code><code class="descname">undoc_header</code><a class="headerlink" href="#cmd.Cmd.undoc_header" title="本定義的永久連結">¶</a></dt> <dd><p>The header to issue if the help output has a section for undocumented commands (that is, there are <code class="xref py py-meth docutils literal notranslate"><span class="pre">do_*()</span></code> methods without corresponding <code class="xref py py-meth docutils literal notranslate"><span class="pre">help_*()</span></code> methods).</p> </dd></dl> <dl class="attribute"> <dt id="cmd.Cmd.ruler"> <code class="descclassname">Cmd.</code><code class="descname">ruler</code><a class="headerlink" href="#cmd.Cmd.ruler" title="本定義的永久連結">¶</a></dt> <dd><p>The character used to draw separator lines under the help-message headers. If empty, no ruler line is drawn. It defaults to <code class="docutils literal notranslate"><span class="pre">'='</span></code>.</p> </dd></dl> <dl class="attribute"> <dt id="cmd.Cmd.use_rawinput"> <code class="descclassname">Cmd.</code><code class="descname">use_rawinput</code><a class="headerlink" href="#cmd.Cmd.use_rawinput" title="本定義的永久連結">¶</a></dt> <dd><p>A flag, defaulting to true. If true, <a class="reference internal" href="#cmd.Cmd.cmdloop" title="cmd.Cmd.cmdloop"><code class="xref py py-meth docutils literal notranslate"><span class="pre">cmdloop()</span></code></a> uses <a class="reference internal" href="functions.html#input" title="input"><code class="xref py py-func docutils literal notranslate"><span class="pre">input()</span></code></a> to display a prompt and read the next command; if false, <code class="xref py py-meth docutils literal notranslate"><span class="pre">sys.stdout.write()</span></code> and <code class="xref py py-meth docutils literal notranslate"><span class="pre">sys.stdin.readline()</span></code> are used. (This means that by importing <a class="reference internal" href="readline.html#module-readline" title="readline: GNU readline support for Python. (Unix)"><code class="xref py py-mod docutils literal notranslate"><span class="pre">readline</span></code></a>, on systems that support it, the interpreter will automatically support <strong class="program">Emacs</strong>-like line editing and command-history keystrokes.)</p> </dd></dl> </div> <div class="section" id="cmd-example"> <span id="id2"></span><h2>25.2.2. Cmd Example<a class="headerlink" href="#cmd-example" title="本標題的永久連結">¶</a></h2> <p>The <a class="reference internal" href="#module-cmd" title="cmd: Build line-oriented command interpreters."><code class="xref py py-mod docutils literal notranslate"><span class="pre">cmd</span></code></a> module is mainly useful for building custom shells that let a user work with a program interactively.</p> <p>This section presents a simple example of how to build a shell around a few of the commands in the <a class="reference internal" href="turtle.html#module-turtle" title="turtle: An educational framework for simple graphics applications"><code class="xref py py-mod docutils literal notranslate"><span class="pre">turtle</span></code></a> module.</p> <p>Basic turtle commands such as <a class="reference internal" href="turtle.html#turtle.forward" title="turtle.forward"><code class="xref py py-meth docutils literal notranslate"><span class="pre">forward()</span></code></a> are added to a <a class="reference internal" href="#cmd.Cmd" title="cmd.Cmd"><code class="xref py py-class docutils literal notranslate"><span class="pre">Cmd</span></code></a> subclass with method named <code class="xref py py-meth docutils literal notranslate"><span class="pre">do_forward()</span></code>. The argument is converted to a number and dispatched to the turtle module. The docstring is used in the help utility provided by the shell.</p> <p>The example also includes a basic record and playback facility implemented with the <a class="reference internal" href="#cmd.Cmd.precmd" title="cmd.Cmd.precmd"><code class="xref py py-meth docutils literal notranslate"><span class="pre">precmd()</span></code></a> method which is responsible for converting the input to lowercase and writing the commands to a file. The <code class="xref py py-meth docutils literal notranslate"><span class="pre">do_playback()</span></code> method reads the file and adds the recorded commands to the <code class="xref py py-attr docutils literal notranslate"><span class="pre">cmdqueue</span></code> for immediate playback:</p> <div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="kn">import</span> <span class="nn">cmd</span><span class="o">,</span> <span class="nn">sys</span> <span class="kn">from</span> <span class="nn">turtle</span> <span class="k">import</span> <span class="o">*</span> <span class="k">class</span> <span class="nc">TurtleShell</span><span class="p">(</span><span class="n">cmd</span><span class="o">.</span><span class="n">Cmd</span><span class="p">):</span> <span class="n">intro</span> <span class="o">=</span> <span class="s1">'Welcome to the turtle shell. Type help or ? to list commands.</span><span class="se">\n</span><span class="s1">'</span> <span class="n">prompt</span> <span class="o">=</span> <span class="s1">'(turtle) '</span> <span class="n">file</span> <span class="o">=</span> <span class="kc">None</span> <span class="c1"># ----- basic turtle commands -----</span> <span class="k">def</span> <span class="nf">do_forward</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">arg</span><span class="p">):</span> <span class="s1">'Move the turtle forward by the specified distance: FORWARD 10'</span> <span class="n">forward</span><span class="p">(</span><span class="o">*</span><span class="n">parse</span><span class="p">(</span><span class="n">arg</span><span class="p">))</span> <span class="k">def</span> <span class="nf">do_right</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">arg</span><span class="p">):</span> <span class="s1">'Turn turtle right by given number of degrees: RIGHT 20'</span> <span class="n">right</span><span class="p">(</span><span class="o">*</span><span class="n">parse</span><span class="p">(</span><span class="n">arg</span><span class="p">))</span> <span class="k">def</span> <span class="nf">do_left</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">arg</span><span class="p">):</span> <span class="s1">'Turn turtle left by given number of degrees: LEFT 90'</span> <span class="n">left</span><span class="p">(</span><span class="o">*</span><span class="n">parse</span><span class="p">(</span><span class="n">arg</span><span class="p">))</span> <span class="k">def</span> <span class="nf">do_goto</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">arg</span><span class="p">):</span> <span class="s1">'Move turtle to an absolute position with changing orientation. GOTO 100 200'</span> <span class="n">goto</span><span class="p">(</span><span class="o">*</span><span class="n">parse</span><span class="p">(</span><span class="n">arg</span><span class="p">))</span> <span class="k">def</span> <span class="nf">do_home</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">arg</span><span class="p">):</span> <span class="s1">'Return turtle to the home position: HOME'</span> <span class="n">home</span><span class="p">()</span> <span class="k">def</span> <span class="nf">do_circle</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">arg</span><span class="p">):</span> <span class="s1">'Draw circle with given radius an options extent and steps: CIRCLE 50'</span> <span class="n">circle</span><span class="p">(</span><span class="o">*</span><span class="n">parse</span><span class="p">(</span><span class="n">arg</span><span class="p">))</span> <span class="k">def</span> <span class="nf">do_position</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">arg</span><span class="p">):</span> <span class="s1">'Print the current turtle position: POSITION'</span> <span class="nb">print</span><span class="p">(</span><span class="s1">'Current position is </span><span class="si">%d</span><span class="s1"> </span><span class="si">%d</span><span class="se">\n</span><span class="s1">'</span> <span class="o">%</span> <span class="n">position</span><span class="p">())</span> <span class="k">def</span> <span class="nf">do_heading</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">arg</span><span class="p">):</span> <span class="s1">'Print the current turtle heading in degrees: HEADING'</span> <span class="nb">print</span><span class="p">(</span><span class="s1">'Current heading is </span><span class="si">%d</span><span class="se">\n</span><span class="s1">'</span> <span class="o">%</span> <span class="p">(</span><span class="n">heading</span><span class="p">(),))</span> <span class="k">def</span> <span class="nf">do_color</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">arg</span><span class="p">):</span> <span class="s1">'Set the color: COLOR BLUE'</span> <span class="n">color</span><span class="p">(</span><span class="n">arg</span><span class="o">.</span><span class="n">lower</span><span class="p">())</span> <span class="k">def</span> <span class="nf">do_undo</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">arg</span><span class="p">):</span> <span class="s1">'Undo (repeatedly) the last turtle action(s): UNDO'</span> <span class="k">def</span> <span class="nf">do_reset</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">arg</span><span class="p">):</span> <span class="s1">'Clear the screen and return turtle to center: RESET'</span> <span class="n">reset</span><span class="p">()</span> <span class="k">def</span> <span class="nf">do_bye</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">arg</span><span class="p">):</span> <span class="s1">'Stop recording, close the turtle window, and exit: BYE'</span> <span class="nb">print</span><span class="p">(</span><span class="s1">'Thank you for using Turtle'</span><span class="p">)</span> <span class="bp">self</span><span class="o">.</span><span class="n">close</span><span class="p">()</span> <span class="n">bye</span><span class="p">()</span> <span class="k">return</span> <span class="kc">True</span> <span class="c1"># ----- record and playback -----</span> <span class="k">def</span> <span class="nf">do_record</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">arg</span><span class="p">):</span> <span class="s1">'Save future commands to filename: RECORD rose.cmd'</span> <span class="bp">self</span><span class="o">.</span><span class="n">file</span> <span class="o">=</span> <span class="nb">open</span><span class="p">(</span><span class="n">arg</span><span class="p">,</span> <span class="s1">'w'</span><span class="p">)</span> <span class="k">def</span> <span class="nf">do_playback</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">arg</span><span class="p">):</span> <span class="s1">'Playback commands from a file: PLAYBACK rose.cmd'</span> <span class="bp">self</span><span class="o">.</span><span class="n">close</span><span class="p">()</span> <span class="k">with</span> <span class="nb">open</span><span class="p">(</span><span class="n">arg</span><span class="p">)</span> <span class="k">as</span> <span class="n">f</span><span class="p">:</span> <span class="bp">self</span><span class="o">.</span><span class="n">cmdqueue</span><span class="o">.</span><span class="n">extend</span><span class="p">(</span><span class="n">f</span><span class="o">.</span><span class="n">read</span><span class="p">()</span><span class="o">.</span><span class="n">splitlines</span><span class="p">())</span> <span class="k">def</span> <span class="nf">precmd</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">line</span><span class="p">):</span> <span class="n">line</span> <span class="o">=</span> <span class="n">line</span><span class="o">.</span><span class="n">lower</span><span class="p">()</span> <span class="k">if</span> <span class="bp">self</span><span class="o">.</span><span class="n">file</span> <span class="ow">and</span> <span class="s1">'playback'</span> <span class="ow">not</span> <span class="ow">in</span> <span class="n">line</span><span class="p">:</span> <span class="nb">print</span><span class="p">(</span><span class="n">line</span><span class="p">,</span> <span class="n">file</span><span class="o">=</span><span class="bp">self</span><span class="o">.</span><span class="n">file</span><span class="p">)</span> <span class="k">return</span> <span class="n">line</span> <span class="k">def</span> <span class="nf">close</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span> <span class="k">if</span> <span class="bp">self</span><span class="o">.</span><span class="n">file</span><span class="p">:</span> <span class="bp">self</span><span class="o">.</span><span class="n">file</span><span class="o">.</span><span class="n">close</span><span class="p">()</span> <span class="bp">self</span><span class="o">.</span><span class="n">file</span> <span class="o">=</span> <span class="kc">None</span> <span class="k">def</span> <span class="nf">parse</span><span class="p">(</span><span class="n">arg</span><span class="p">):</span> <span class="s1">'Convert a series of zero or more numbers to an argument tuple'</span> <span class="k">return</span> <span class="nb">tuple</span><span class="p">(</span><span class="nb">map</span><span class="p">(</span><span class="nb">int</span><span class="p">,</span> <span class="n">arg</span><span class="o">.</span><span class="n">split</span><span class="p">()))</span> <span class="k">if</span> <span class="vm">__name__</span> <span class="o">==</span> <span class="s1">'__main__'</span><span class="p">:</span> <span class="n">TurtleShell</span><span class="p">()</span><span class="o">.</span><span class="n">cmdloop</span><span class="p">()</span> </pre></div> </div> <p>Here is a sample session with the turtle shell showing the help functions, using blank lines to repeat commands, and the simple record and playback facility:</p> <div class="highlight-none notranslate"><div class="highlight"><pre><span></span>Welcome to the turtle shell. Type help or ? to list commands. (turtle) ? Documented commands (type help <topic>): ======================================== bye color goto home playback record right circle forward heading left position reset undo (turtle) help forward Move the turtle forward by the specified distance: FORWARD 10 (turtle) record spiral.cmd (turtle) position Current position is 0 0 (turtle) heading Current heading is 0 (turtle) reset (turtle) circle 20 (turtle) right 30 (turtle) circle 40 (turtle) right 30 (turtle) circle 60 (turtle) right 30 (turtle) circle 80 (turtle) right 30 (turtle) circle 100 (turtle) right 30 (turtle) circle 120 (turtle) right 30 (turtle) circle 120 (turtle) heading Current heading is 180 (turtle) forward 100 (turtle) (turtle) right 90 (turtle) forward 100 (turtle) (turtle) right 90 (turtle) forward 400 (turtle) right 90 (turtle) forward 500 (turtle) right 90 (turtle) forward 400 (turtle) right 90 (turtle) forward 300 (turtle) playback spiral.cmd Current position is 0 0 Current heading is 0 Current heading is 180 (turtle) bye Thank you for using Turtle </pre></div> </div> </div> </div> </div> </div> </div> <div class="sphinxsidebar" role="navigation" aria-label="main navigation"> <div class="sphinxsidebarwrapper"> <h3><a href="../contents.html">目錄</a></h3> <ul> <li><a class="reference internal" href="#">25.2. <code class="docutils literal notranslate"><span class="pre">cmd</span></code> — Support for line-oriented command interpreters</a><ul> <li><a class="reference internal" href="#cmd-objects">25.2.1. Cmd Objects</a></li> <li><a class="reference internal" href="#cmd-example">25.2.2. Cmd Example</a></li> </ul> </li> </ul> <h4>上個主題</h4> <p class="topless"><a href="turtle.html" title="上一章">25.1. <code class="docutils literal notranslate"><span class="pre">turtle</span></code> — 龜圖學</a></p> <h4>下個主題</h4> <p class="topless"><a href="shlex.html" title="下一章">25.3. <code class="docutils literal notranslate"><span class="pre">shlex</span></code> — Simple lexical analysis</a></p> <div role="note" aria-label="source link"> <h3>This Page</h3> <ul class="this-page-menu"> <li><a href="../bugs.html">Report a Bug</a></li> <li> <a href="https://github.com/python/cpython/blob/3.7/Doc/library/cmd.rst" rel="nofollow">Show Source </a> </li> </ul> </div> </div> </div> <div class="clearer"></div> </div> <div class="related" role="navigation" aria-label="related navigation"> <h3>瀏覽</h3> <ul> <li class="right" style="margin-right: 10px"> <a href="../genindex.html" title="General Index" >索引</a></li> <li class="right" > <a href="../py-modindex.html" title="Python 模組索引" >模組</a> |</li> <li class="right" > <a href="shlex.html" title="25.3. shlex — Simple lexical analysis" >下一頁</a> |</li> <li class="right" > <a href="turtle.html" title="25.1. turtle — 龜圖學" >上一頁</a> |</li> <li><img src="../_static/py.png" alt="" style="vertical-align: middle; margin-top: -1px"/></li> <li><a href="https://www.python.org/">Python</a> »</li> <li> <span class="language_switcher_placeholder">zh_TW</span> <span class="version_switcher_placeholder">3.7.0</span> <a href="../index.html">Documentation </a> » </li> <li class="nav-item nav-item-1"><a href="index.html" >Python 標準函式庫 (Standard Library)</a> »</li> <li class="nav-item nav-item-2"><a href="frameworks.html" >25. 程式框架</a> »</li> <li class="right"> <div class="inline-search" style="display: none" role="search"> <form class="inline-search" action="../search.html" method="get"> <input placeholder="Quick search" type="text" name="q" /> <input type="submit" value="Go" /> <input type="hidden" name="check_keywords" value="yes" /> <input type="hidden" name="area" value="default" /> </form> </div> <script type="text/javascript">$('.inline-search').show(0);</script> | </li> </ul> </div> <div class="footer"> © <a href="../copyright.html">Copyright</a> 2001-2018, Python Software Foundation. <br /> The Python Software Foundation is a non-profit corporation. <a href="https://www.python.org/psf/donations/">Please donate.</a> <br /> Last updated on 8月 22, 2018. <a href="../bugs.html">Found a bug</a>? <br /> Created using <a href="http://sphinx.pocoo.org/">Sphinx</a> 1.7.7. </div> </body> </html> |
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