1 2<!DOCTYPE html> 3 4<html> 5 <head> 6 <meta charset="utf-8" /> 7 <meta name="viewport" content="width=device-width, initial-scale=1.0" /> 8 <title>IDLE — Python 3.11.0a0 documentation</title> 9 <link rel="stylesheet" href="../_static/pydoctheme.css" type="text/css" /> 10 <link rel="stylesheet" href="../_static/pygments.css" type="text/css" /> 11 12 <script id="documentation_options" data-url_root="../" src="../_static/documentation_options.js"></script> 13 <script src="../_static/jquery.js"></script> 14 <script src="../_static/underscore.js"></script> 15 <script src="../_static/doctools.js"></script> 16 <script src="../_static/language_data.js"></script> 17 18 <script src="../_static/sidebar.js"></script> 19 20 <link rel="search" type="application/opensearchdescription+xml" 21 title="Search within Python 3.11.0a0 documentation" 22 href="../_static/opensearch.xml"/> 23 <link rel="author" title="About these documents" href="../about.html" /> 24 <link rel="index" title="Index" href="../genindex.html" /> 25 <link rel="search" title="Search" href="../search.html" /> 26 <link rel="copyright" title="Copyright" href="../copyright.html" /> 27 <link rel="next" title="Development Tools" href="development.html" /> 28 <link rel="prev" title="tkinter.tix — Extension widgets for Tk" href="tkinter.tix.html" /> 29 <link rel="canonical" href="https://docs.python.org/3/library/idle.html" /> 30 31 32 33 34 35 <style> 36 @media only screen { 37 table.full-width-table { 38 width: 100%; 39 } 40 } 41 </style> 42 43 <link rel="shortcut icon" type="image/png" href="../_static/py.png" /> 44 45 <script type="text/javascript" src="../_static/copybutton.js"></script> 46 47 48 49 50 </head><body> 51 52 <div class="related" role="navigation" aria-label="related navigation"> 53 <h3>Navigation</h3> 54 <ul> 55 <li class="right" style="margin-right: 10px"> 56 <a href="../genindex.html" title="General Index" 57 accesskey="I">index</a></li> 58 <li class="right" > 59 <a href="../py-modindex.html" title="Python Module Index" 60 >modules</a> |</li> 61 <li class="right" > 62 <a href="development.html" title="Development Tools" 63 accesskey="N">next</a> |</li> 64 <li class="right" > 65 <a href="tkinter.tix.html" title="tkinter.tix — Extension widgets for Tk" 66 accesskey="P">previous</a> |</li> 67 68 <li><img src="../_static/py.png" alt="" 69 style="vertical-align: middle; margin-top: -1px"/></li> 70 <li><a href="https://www.python.org/">Python</a> »</li> 71 72 73 <li id="cpython-language-and-version"> 74 <a href="../index.html">3.11.0a0 Documentation</a> » 75 </li> 76 77 <li class="nav-item nav-item-1"><a href="index.html" >The Python Standard Library</a> »</li> 78 <li class="nav-item nav-item-2"><a href="tk.html" accesskey="U">Graphical User Interfaces with Tk</a> »</li> 79 <li class="nav-item nav-item-this"><a href="">IDLE</a></li> 80 <li class="right"> 81 82 83 <div class="inline-search" style="display: none" role="search"> 84 <form class="inline-search" action="../search.html" method="get"> 85 <input placeholder="Quick search" type="text" name="q" /> 86 <input type="submit" value="Go" /> 87 <input type="hidden" name="check_keywords" value="yes" /> 88 <input type="hidden" name="area" value="default" /> 89 </form> 90 </div> 91 <script type="text/javascript">$('.inline-search').show(0);</script> 92 | 93 </li> 94 95 </ul> 96 </div> 97 98 <div class="document"> 99 <div class="documentwrapper"> 100 <div class="bodywrapper"> 101 <div class="body" role="main"> 102 103 <div class="section" id="idle"> 104<span id="id1"></span><h1>IDLE<a class="headerlink" href="#idle" title="Permalink to this headline">¶</a></h1> 105<p><strong>Source code:</strong> <a class="reference external" href="https://github.com/python/cpython/tree/main/Lib/idlelib/">Lib/idlelib/</a></p> 106<hr class="docutils" id="index-0" /> 107<p>IDLE is Python’s Integrated Development and Learning Environment.</p> 108<p>IDLE has the following features:</p> 109<ul class="simple"> 110<li><p>coded in 100% pure Python, using the <a class="reference internal" href="tkinter.html#module-tkinter" title="tkinter: Interface to Tcl/Tk for graphical user interfaces"><code class="xref py py-mod docutils literal notranslate"><span class="pre">tkinter</span></code></a> GUI toolkit</p></li> 111<li><p>cross-platform: works mostly the same on Windows, Unix, and macOS</p></li> 112<li><p>Python shell window (interactive interpreter) with colorizing 113of code input, output, and error messages</p></li> 114<li><p>multi-window text editor with multiple undo, Python colorizing, 115smart indent, call tips, auto completion, and other features</p></li> 116<li><p>search within any window, replace within editor windows, and search 117through multiple files (grep)</p></li> 118<li><p>debugger with persistent breakpoints, stepping, and viewing 119of global and local namespaces</p></li> 120<li><p>configuration, browsers, and other dialogs</p></li> 121</ul> 122<div class="section" id="menus"> 123<h2>Menus<a class="headerlink" href="#menus" title="Permalink to this headline">¶</a></h2> 124<p>IDLE has two main window types, the Shell window and the Editor window. It is 125possible to have multiple editor windows simultaneously. On Windows and 126Linux, each has its own top menu. Each menu documented below indicates 127which window type it is associated with.</p> 128<p>Output windows, such as used for Edit => Find in Files, are a subtype of editor 129window. They currently have the same top menu but a different 130default title and context menu.</p> 131<p>On macOS, there is one application menu. It dynamically changes according 132to the window currently selected. It has an IDLE menu, and some entries 133described below are moved around to conform to Apple guidelines.</p> 134<div class="section" id="file-menu-shell-and-editor"> 135<h3>File menu (Shell and Editor)<a class="headerlink" href="#file-menu-shell-and-editor" title="Permalink to this headline">¶</a></h3> 136<dl class="simple"> 137<dt>New File</dt><dd><p>Create a new file editing window.</p> 138</dd> 139<dt>Open…</dt><dd><p>Open an existing file with an Open dialog.</p> 140</dd> 141<dt>Recent Files</dt><dd><p>Open a list of recent files. Click one to open it.</p> 142</dd> 143<dt>Open Module…</dt><dd><p>Open an existing module (searches sys.path).</p> 144</dd> 145</dl> 146<dl class="simple" id="index-1"> 147<dt>Class Browser</dt><dd><p>Show functions, classes, and methods in the current Editor file in a 148tree structure. In the shell, open a module first.</p> 149</dd> 150<dt>Path Browser</dt><dd><p>Show sys.path directories, modules, functions, classes and methods in a 151tree structure.</p> 152</dd> 153<dt>Save</dt><dd><p>Save the current window to the associated file, if there is one. Windows 154that have been changed since being opened or last saved have a * before 155and after the window title. If there is no associated file, 156do Save As instead.</p> 157</dd> 158<dt>Save As…</dt><dd><p>Save the current window with a Save As dialog. The file saved becomes the 159new associated file for the window.</p> 160</dd> 161<dt>Save Copy As…</dt><dd><p>Save the current window to different file without changing the associated 162file.</p> 163</dd> 164<dt>Print Window</dt><dd><p>Print the current window to the default printer.</p> 165</dd> 166<dt>Close</dt><dd><p>Close the current window (ask to save if unsaved).</p> 167</dd> 168<dt>Exit</dt><dd><p>Close all windows and quit IDLE (ask to save unsaved windows).</p> 169</dd> 170</dl> 171</div> 172<div class="section" id="edit-menu-shell-and-editor"> 173<h3>Edit menu (Shell and Editor)<a class="headerlink" href="#edit-menu-shell-and-editor" title="Permalink to this headline">¶</a></h3> 174<dl class="simple"> 175<dt>Undo</dt><dd><p>Undo the last change to the current window. A maximum of 1000 changes may 176be undone.</p> 177</dd> 178<dt>Redo</dt><dd><p>Redo the last undone change to the current window.</p> 179</dd> 180<dt>Cut</dt><dd><p>Copy selection into the system-wide clipboard; then delete the selection.</p> 181</dd> 182<dt>Copy</dt><dd><p>Copy selection into the system-wide clipboard.</p> 183</dd> 184<dt>Paste</dt><dd><p>Insert contents of the system-wide clipboard into the current window.</p> 185</dd> 186</dl> 187<p>The clipboard functions are also available in context menus.</p> 188<dl class="simple"> 189<dt>Select All</dt><dd><p>Select the entire contents of the current window.</p> 190</dd> 191<dt>Find…</dt><dd><p>Open a search dialog with many options</p> 192</dd> 193<dt>Find Again</dt><dd><p>Repeat the last search, if there is one.</p> 194</dd> 195<dt>Find Selection</dt><dd><p>Search for the currently selected string, if there is one.</p> 196</dd> 197<dt>Find in Files…</dt><dd><p>Open a file search dialog. Put results in a new output window.</p> 198</dd> 199<dt>Replace…</dt><dd><p>Open a search-and-replace dialog.</p> 200</dd> 201<dt>Go to Line</dt><dd><p>Move the cursor to the beginning of the line requested and make that 202line visible. A request past the end of the file goes to the end. 203Clear any selection and update the line and column status.</p> 204</dd> 205<dt>Show Completions</dt><dd><p>Open a scrollable list allowing selection of existing names. See 206<a class="reference internal" href="#completions"><span class="std std-ref">Completions</span></a> in the Editing and navigation section below.</p> 207</dd> 208<dt>Expand Word</dt><dd><p>Expand a prefix you have typed to match a full word in the same window; 209repeat to get a different expansion.</p> 210</dd> 211<dt>Show call tip</dt><dd><p>After an unclosed parenthesis for a function, open a small window with 212function parameter hints. See <a class="reference internal" href="#calltips"><span class="std std-ref">Calltips</span></a> in the 213Editing and navigation section below.</p> 214</dd> 215<dt>Show surrounding parens</dt><dd><p>Highlight the surrounding parenthesis.</p> 216</dd> 217</dl> 218</div> 219<div class="section" id="format-menu-editor-window-only"> 220<span id="format-menu"></span><h3>Format menu (Editor window only)<a class="headerlink" href="#format-menu-editor-window-only" title="Permalink to this headline">¶</a></h3> 221<dl class="simple"> 222<dt>Indent Region</dt><dd><p>Shift selected lines right by the indent width (default 4 spaces).</p> 223</dd> 224<dt>Dedent Region</dt><dd><p>Shift selected lines left by the indent width (default 4 spaces).</p> 225</dd> 226<dt>Comment Out Region</dt><dd><p>Insert ## in front of selected lines.</p> 227</dd> 228<dt>Uncomment Region</dt><dd><p>Remove leading # or ## from selected lines.</p> 229</dd> 230<dt>Tabify Region</dt><dd><p>Turn <em>leading</em> stretches of spaces into tabs. (Note: We recommend using 2314 space blocks to indent Python code.)</p> 232</dd> 233<dt>Untabify Region</dt><dd><p>Turn <em>all</em> tabs into the correct number of spaces.</p> 234</dd> 235<dt>Toggle Tabs</dt><dd><p>Open a dialog to switch between indenting with spaces and tabs.</p> 236</dd> 237<dt>New Indent Width</dt><dd><p>Open a dialog to change indent width. The accepted default by the Python 238community is 4 spaces.</p> 239</dd> 240<dt>Format Paragraph</dt><dd><p>Reformat the current blank-line-delimited paragraph in comment block or 241multiline string or selected line in a string. All lines in the 242paragraph will be formatted to less than N columns, where N defaults to 72.</p> 243</dd> 244<dt>Strip trailing whitespace</dt><dd><p>Remove trailing space and other whitespace characters after the last 245non-whitespace character of a line by applying str.rstrip to each line, 246including lines within multiline strings. Except for Shell windows, 247remove extra newlines at the end of the file.</p> 248</dd> 249</dl> 250</div> 251<div class="section" id="run-menu-editor-window-only"> 252<span id="index-2"></span><h3>Run menu (Editor window only)<a class="headerlink" href="#run-menu-editor-window-only" title="Permalink to this headline">¶</a></h3> 253<dl class="simple" id="run-module"> 254<dt>Run Module</dt><dd><p>Do <a class="reference internal" href="#check-module"><span class="std std-ref">Check Module</span></a>. If no error, restart the shell to clean the 255environment, then execute the module. Output is displayed in the Shell 256window. Note that output requires use of <code class="docutils literal notranslate"><span class="pre">print</span></code> or <code class="docutils literal notranslate"><span class="pre">write</span></code>. 257When execution is complete, the Shell retains focus and displays a prompt. 258At this point, one may interactively explore the result of execution. 259This is similar to executing a file with <code class="docutils literal notranslate"><span class="pre">python</span> <span class="pre">-i</span> <span class="pre">file</span></code> at a command 260line.</p> 261</dd> 262</dl> 263<dl class="simple" id="run-custom"> 264<dt>Run… Customized</dt><dd><p>Same as <a class="reference internal" href="#run-module"><span class="std std-ref">Run Module</span></a>, but run the module with customized 265settings. <em>Command Line Arguments</em> extend <a class="reference internal" href="sys.html#sys.argv" title="sys.argv"><code class="xref py py-data docutils literal notranslate"><span class="pre">sys.argv</span></code></a> as if passed 266on a command line. The module can be run in the Shell without restarting.</p> 267</dd> 268</dl> 269<dl class="simple" id="check-module"> 270<dt>Check Module</dt><dd><p>Check the syntax of the module currently open in the Editor window. If the 271module has not been saved IDLE will either prompt the user to save or 272autosave, as selected in the General tab of the Idle Settings dialog. If 273there is a syntax error, the approximate location is indicated in the 274Editor window.</p> 275</dd> 276</dl> 277<dl class="simple" id="python-shell"> 278<dt>Python Shell</dt><dd><p>Open or wake up the Python Shell window.</p> 279</dd> 280</dl> 281</div> 282<div class="section" id="shell-menu-shell-window-only"> 283<h3>Shell menu (Shell window only)<a class="headerlink" href="#shell-menu-shell-window-only" title="Permalink to this headline">¶</a></h3> 284<dl class="simple"> 285<dt>View Last Restart</dt><dd><p>Scroll the shell window to the last Shell restart.</p> 286</dd> 287<dt>Restart Shell</dt><dd><p>Restart the shell to clean the environment and reset display and exception handling.</p> 288</dd> 289<dt>Previous History</dt><dd><p>Cycle through earlier commands in history which match the current entry.</p> 290</dd> 291<dt>Next History</dt><dd><p>Cycle through later commands in history which match the current entry.</p> 292</dd> 293<dt>Interrupt Execution</dt><dd><p>Stop a running program.</p> 294</dd> 295</dl> 296</div> 297<div class="section" id="debug-menu-shell-window-only"> 298<h3>Debug menu (Shell window only)<a class="headerlink" href="#debug-menu-shell-window-only" title="Permalink to this headline">¶</a></h3> 299<dl class="simple"> 300<dt>Go to File/Line</dt><dd><p>Look on the current line. with the cursor, and the line above for a filename 301and line number. If found, open the file if not already open, and show the 302line. Use this to view source lines referenced in an exception traceback 303and lines found by Find in Files. Also available in the context menu of 304the Shell window and Output windows.</p> 305</dd> 306</dl> 307<dl class="simple" id="index-3"> 308<dt>Debugger (toggle)</dt><dd><p>When activated, code entered in the Shell or run from an Editor will run 309under the debugger. In the Editor, breakpoints can be set with the context 310menu. This feature is still incomplete and somewhat experimental.</p> 311</dd> 312<dt>Stack Viewer</dt><dd><p>Show the stack traceback of the last exception in a tree widget, with 313access to locals and globals.</p> 314</dd> 315<dt>Auto-open Stack Viewer</dt><dd><p>Toggle automatically opening the stack viewer on an unhandled exception.</p> 316</dd> 317</dl> 318</div> 319<div class="section" id="options-menu-shell-and-editor"> 320<h3>Options menu (Shell and Editor)<a class="headerlink" href="#options-menu-shell-and-editor" title="Permalink to this headline">¶</a></h3> 321<dl class="simple"> 322<dt>Configure IDLE</dt><dd><p>Open a configuration dialog and change preferences for the following: 323fonts, indentation, keybindings, text color themes, startup windows and 324size, additional help sources, and extensions. On macOS, open the 325configuration dialog by selecting Preferences in the application 326menu. For more details, see 327<a class="reference internal" href="#preferences"><span class="std std-ref">Setting preferences</span></a> under Help and preferences.</p> 328</dd> 329</dl> 330<p>Most configuration options apply to all windows or all future windows. 331The option items below only apply to the active window.</p> 332<dl class="simple"> 333<dt>Show/Hide Code Context (Editor Window only)</dt><dd><p>Open a pane at the top of the edit window which shows the block context 334of the code which has scrolled above the top of the window. See 335<a class="reference internal" href="#code-context"><span class="std std-ref">Code Context</span></a> in the Editing and Navigation section 336below.</p> 337</dd> 338<dt>Show/Hide Line Numbers (Editor Window only)</dt><dd><p>Open a column to the left of the edit window which shows the number 339of each line of text. The default is off, which may be changed in the 340preferences (see <a class="reference internal" href="#preferences"><span class="std std-ref">Setting preferences</span></a>).</p> 341</dd> 342<dt>Zoom/Restore Height</dt><dd><p>Toggles the window between normal size and maximum height. The initial size 343defaults to 40 lines by 80 chars unless changed on the General tab of the 344Configure IDLE dialog. The maximum height for a screen is determined by 345momentarily maximizing a window the first time one is zoomed on the screen. 346Changing screen settings may invalidate the saved height. This toggle has 347no effect when a window is maximized.</p> 348</dd> 349</dl> 350</div> 351<div class="section" id="window-menu-shell-and-editor"> 352<h3>Window menu (Shell and Editor)<a class="headerlink" href="#window-menu-shell-and-editor" title="Permalink to this headline">¶</a></h3> 353<p>Lists the names of all open windows; select one to bring it to the foreground 354(deiconifying it if necessary).</p> 355</div> 356<div class="section" id="help-menu-shell-and-editor"> 357<h3>Help menu (Shell and Editor)<a class="headerlink" href="#help-menu-shell-and-editor" title="Permalink to this headline">¶</a></h3> 358<dl class="simple"> 359<dt>About IDLE</dt><dd><p>Display version, copyright, license, credits, and more.</p> 360</dd> 361<dt>IDLE Help</dt><dd><p>Display this IDLE document, detailing the menu options, basic editing and 362navigation, and other tips.</p> 363</dd> 364<dt>Python Docs</dt><dd><p>Access local Python documentation, if installed, or start a web browser 365and open docs.python.org showing the latest Python documentation.</p> 366</dd> 367<dt>Turtle Demo</dt><dd><p>Run the turtledemo module with example Python code and turtle drawings.</p> 368</dd> 369</dl> 370<p>Additional help sources may be added here with the Configure IDLE dialog under 371the General tab. See the <a class="reference internal" href="#help-sources"><span class="std std-ref">Help sources</span></a> subsection below 372for more on Help menu choices.</p> 373</div> 374<div class="section" id="context-menus"> 375<span id="index-4"></span><h3>Context Menus<a class="headerlink" href="#context-menus" title="Permalink to this headline">¶</a></h3> 376<p>Open a context menu by right-clicking in a window (Control-click on macOS). 377Context menus have the standard clipboard functions also on the Edit menu.</p> 378<dl class="simple"> 379<dt>Cut</dt><dd><p>Copy selection into the system-wide clipboard; then delete the selection.</p> 380</dd> 381<dt>Copy</dt><dd><p>Copy selection into the system-wide clipboard.</p> 382</dd> 383<dt>Paste</dt><dd><p>Insert contents of the system-wide clipboard into the current window.</p> 384</dd> 385</dl> 386<p>Editor windows also have breakpoint functions. Lines with a breakpoint set are 387specially marked. Breakpoints only have an effect when running under the 388debugger. Breakpoints for a file are saved in the user’s <code class="docutils literal notranslate"><span class="pre">.idlerc</span></code> 389directory.</p> 390<dl class="simple"> 391<dt>Set Breakpoint</dt><dd><p>Set a breakpoint on the current line.</p> 392</dd> 393<dt>Clear Breakpoint</dt><dd><p>Clear the breakpoint on that line.</p> 394</dd> 395</dl> 396<p>Shell and Output windows also have the following.</p> 397<dl class="simple"> 398<dt>Go to file/line</dt><dd><p>Same as in Debug menu.</p> 399</dd> 400</dl> 401<p>The Shell window also has an output squeezing facility explained in the <em>Python 402Shell window</em> subsection below.</p> 403<dl class="simple"> 404<dt>Squeeze</dt><dd><p>If the cursor is over an output line, squeeze all the output between 405the code above and the prompt below down to a ‘Squeezed text’ label.</p> 406</dd> 407</dl> 408</div> 409</div> 410<div class="section" id="editing-and-navigation"> 411<span id="id2"></span><h2>Editing and navigation<a class="headerlink" href="#editing-and-navigation" title="Permalink to this headline">¶</a></h2> 412<div class="section" id="editor-windows"> 413<h3>Editor windows<a class="headerlink" href="#editor-windows" title="Permalink to this headline">¶</a></h3> 414<p>IDLE may open editor windows when it starts, depending on settings 415and how you start IDLE. Thereafter, use the File menu. There can be only 416one open editor window for a given file.</p> 417<p>The title bar contains the name of the file, the full path, and the version 418of Python and IDLE running the window. The status bar contains the line 419number (‘Ln’) and column number (‘Col’). Line numbers start with 1; 420column numbers with 0.</p> 421<p>IDLE assumes that files with a known .py* extension contain Python code 422and that other files do not. Run Python code with the Run menu.</p> 423</div> 424<div class="section" id="key-bindings"> 425<h3>Key bindings<a class="headerlink" href="#key-bindings" title="Permalink to this headline">¶</a></h3> 426<p>In this section, ‘C’ refers to the <kbd class="kbd docutils literal notranslate">Control</kbd> key on Windows and Unix and 427the <kbd class="kbd docutils literal notranslate">Command</kbd> key on macOS.</p> 428<ul> 429<li><p><kbd class="kbd docutils literal notranslate">Backspace</kbd> deletes to the left; <kbd class="kbd docutils literal notranslate">Del</kbd> deletes to the right</p></li> 430<li><p><kbd class="kbd docutils literal notranslate"><kbd class="kbd docutils literal notranslate">C</kbd>-<kbd class="kbd docutils literal notranslate">Backspace</kbd></kbd> delete word left; <kbd class="kbd docutils literal notranslate"><kbd class="kbd docutils literal notranslate">C</kbd>-<kbd class="kbd docutils literal notranslate">Del</kbd></kbd> delete word to the right</p></li> 431<li><p>Arrow keys and <kbd class="kbd docutils literal notranslate"><kbd class="kbd docutils literal notranslate">Page</kbd> <kbd class="kbd docutils literal notranslate">Up</kbd></kbd>/<kbd class="kbd docutils literal notranslate"><kbd class="kbd docutils literal notranslate">Page</kbd> <kbd class="kbd docutils literal notranslate">Down</kbd></kbd> to move around</p></li> 432<li><p><kbd class="kbd docutils literal notranslate"><kbd class="kbd docutils literal notranslate">C</kbd>-<kbd class="kbd docutils literal notranslate">LeftArrow</kbd></kbd> and <kbd class="kbd docutils literal notranslate"><kbd class="kbd docutils literal notranslate">C</kbd>-<kbd class="kbd docutils literal notranslate">RightArrow</kbd></kbd> moves by words</p></li> 433<li><p><kbd class="kbd docutils literal notranslate">Home</kbd>/<kbd class="kbd docutils literal notranslate">End</kbd> go to begin/end of line</p></li> 434<li><p><kbd class="kbd docutils literal notranslate"><kbd class="kbd docutils literal notranslate">C</kbd>-<kbd class="kbd docutils literal notranslate">Home</kbd></kbd>/<kbd class="kbd docutils literal notranslate"><kbd class="kbd docutils literal notranslate">C</kbd>-<kbd class="kbd docutils literal notranslate">End</kbd></kbd> go to begin/end of file</p></li> 435<li><p>Some useful Emacs bindings are inherited from Tcl/Tk:</p> 436<blockquote> 437<div><ul class="simple"> 438<li><p><kbd class="kbd docutils literal notranslate"><kbd class="kbd docutils literal notranslate">C</kbd>-<kbd class="kbd docutils literal notranslate">a</kbd></kbd> beginning of line</p></li> 439<li><p><kbd class="kbd docutils literal notranslate"><kbd class="kbd docutils literal notranslate">C</kbd>-<kbd class="kbd docutils literal notranslate">e</kbd></kbd> end of line</p></li> 440<li><p><kbd class="kbd docutils literal notranslate"><kbd class="kbd docutils literal notranslate">C</kbd>-<kbd class="kbd docutils literal notranslate">k</kbd></kbd> kill line (but doesn’t put it in clipboard)</p></li> 441<li><p><kbd class="kbd docutils literal notranslate"><kbd class="kbd docutils literal notranslate">C</kbd>-<kbd class="kbd docutils literal notranslate">l</kbd></kbd> center window around the insertion point</p></li> 442<li><p><kbd class="kbd docutils literal notranslate"><kbd class="kbd docutils literal notranslate">C</kbd>-<kbd class="kbd docutils literal notranslate">b</kbd></kbd> go backward one character without deleting (usually you can 443also use the cursor key for this)</p></li> 444<li><p><kbd class="kbd docutils literal notranslate"><kbd class="kbd docutils literal notranslate">C</kbd>-<kbd class="kbd docutils literal notranslate">f</kbd></kbd> go forward one character without deleting (usually you can 445also use the cursor key for this)</p></li> 446<li><p><kbd class="kbd docutils literal notranslate"><kbd class="kbd docutils literal notranslate">C</kbd>-<kbd class="kbd docutils literal notranslate">p</kbd></kbd> go up one line (usually you can also use the cursor key for 447this)</p></li> 448<li><p><kbd class="kbd docutils literal notranslate"><kbd class="kbd docutils literal notranslate">C</kbd>-<kbd class="kbd docutils literal notranslate">d</kbd></kbd> delete next character</p></li> 449</ul> 450</div></blockquote> 451</li> 452</ul> 453<p>Standard keybindings (like <kbd class="kbd docutils literal notranslate"><kbd class="kbd docutils literal notranslate">C</kbd>-<kbd class="kbd docutils literal notranslate">c</kbd></kbd> to copy and <kbd class="kbd docutils literal notranslate"><kbd class="kbd docutils literal notranslate">C</kbd>-<kbd class="kbd docutils literal notranslate">v</kbd></kbd> to paste) 454may work. Keybindings are selected in the Configure IDLE dialog.</p> 455</div> 456<div class="section" id="automatic-indentation"> 457<h3>Automatic indentation<a class="headerlink" href="#automatic-indentation" title="Permalink to this headline">¶</a></h3> 458<p>After a block-opening statement, the next line is indented by 4 spaces (in the 459Python Shell window by one tab). After certain keywords (break, return etc.) 460the next line is dedented. In leading indentation, <kbd class="kbd docutils literal notranslate">Backspace</kbd> deletes up 461to 4 spaces if they are there. <kbd class="kbd docutils literal notranslate">Tab</kbd> inserts spaces (in the Python 462Shell window one tab), number depends on Indent width. Currently, tabs 463are restricted to four spaces due to Tcl/Tk limitations.</p> 464<p>See also the indent/dedent region commands on the 465<a class="reference internal" href="#format-menu"><span class="std std-ref">Format menu</span></a>.</p> 466</div> 467<div class="section" id="completions"> 468<span id="id3"></span><h3>Completions<a class="headerlink" href="#completions" title="Permalink to this headline">¶</a></h3> 469<p>Completions are supplied, when requested and available, for module 470names, attributes of classes or functions, or filenames. Each request 471method displays a completion box with existing names. (See tab 472completions below for an exception.) For any box, change the name 473being completed and the item highlighted in the box by 474typing and deleting characters; by hitting <kbd class="kbd docutils literal notranslate">Up</kbd>, <kbd class="kbd docutils literal notranslate">Down</kbd>, 475<kbd class="kbd docutils literal notranslate">PageUp</kbd>, <kbd class="kbd docutils literal notranslate">PageDown</kbd>, <kbd class="kbd docutils literal notranslate">Home</kbd>, and <kbd class="kbd docutils literal notranslate">End</kbd> keys; 476and by a single click within the box. Close the box with <kbd class="kbd docutils literal notranslate">Escape</kbd>, 477<kbd class="kbd docutils literal notranslate">Enter</kbd>, and double <kbd class="kbd docutils literal notranslate">Tab</kbd> keys or clicks outside the box. 478A double click within the box selects and closes.</p> 479<p>One way to open a box is to type a key character and wait for a 480predefined interval. This defaults to 2 seconds; customize it 481in the settings dialog. (To prevent auto popups, set the delay to a 482large number of milliseconds, such as 100000000.) For imported module 483names or class or function attributes, type ‘.’. 484For filenames in the root directory, type <a class="reference internal" href="os.html#os.sep" title="os.sep"><code class="xref py py-data docutils literal notranslate"><span class="pre">os.sep</span></code></a> or 485<a class="reference internal" href="os.html#os.altsep" title="os.altsep"><code class="xref py py-data docutils literal notranslate"><span class="pre">os.altsep</span></code></a> immediately after an opening quote. (On Windows, 486one can specify a drive first.) Move into subdirectories by typing a 487directory name and a separator.</p> 488<p>Instead of waiting, or after a box is closed, open a completion box 489immediately with Show Completions on the Edit menu. The default hot 490key is <kbd class="kbd docutils literal notranslate"><kbd class="kbd docutils literal notranslate">C</kbd>-<kbd class="kbd docutils literal notranslate">space</kbd></kbd>. If one types a prefix for the desired name 491before opening the box, the first match or near miss is made visible. 492The result is the same as if one enters a prefix 493after the box is displayed. Show Completions after a quote completes 494filenames in the current directory instead of a root directory.</p> 495<p>Hitting <kbd class="kbd docutils literal notranslate">Tab</kbd> after a prefix usually has the same effect as Show 496Completions. (With no prefix, it indents.) However, if there is only 497one match to the prefix, that match is immediately added to the editor 498text without opening a box.</p> 499<p>Invoking ‘Show Completions’, or hitting <kbd class="kbd docutils literal notranslate">Tab</kbd> after a prefix, 500outside of a string and without a preceding ‘.’ opens a box with 501keywords, builtin names, and available module-level names.</p> 502<p>When editing code in an editor (as oppose to Shell), increase the 503available module-level names by running your code 504and not restarting the Shell thereafter. This is especially useful 505after adding imports at the top of a file. This also increases 506possible attribute completions.</p> 507<p>Completion boxes initially exclude names beginning with ‘_’ or, for 508modules, not included in ‘__all__’. The hidden names can be accessed 509by typing ‘_’ after ‘.’, either before or after the box is opened.</p> 510</div> 511<div class="section" id="calltips"> 512<span id="id4"></span><h3>Calltips<a class="headerlink" href="#calltips" title="Permalink to this headline">¶</a></h3> 513<p>A calltip is shown automatically when one types <kbd class="kbd docutils literal notranslate">(</kbd> after the name 514of an <em>accessible</em> function. A function name expression may include 515dots and subscripts. A calltip remains until it is clicked, the cursor 516is moved out of the argument area, or <kbd class="kbd docutils literal notranslate">)</kbd> is typed. Whenever the 517cursor is in the argument part of a definition, select Edit and “Show 518Call Tip” on the menu or enter its shortcut to display a calltip.</p> 519<p>The calltip consists of the function’s signature and docstring up to 520the latter’s first blank line or the fifth non-blank line. (Some builtin 521functions lack an accessible signature.) A ‘/’ or ‘*’ in the signature 522indicates that the preceding or following arguments are passed by 523position or name (keyword) only. Details are subject to change.</p> 524<p>In Shell, the accessible functions depends on what modules have been 525imported into the user process, including those imported by Idle itself, 526and which definitions have been run, all since the last restart.</p> 527<p>For example, restart the Shell and enter <code class="docutils literal notranslate"><span class="pre">itertools.count(</span></code>. A calltip 528appears because Idle imports itertools into the user process for its own 529use. (This could change.) Enter <code class="docutils literal notranslate"><span class="pre">turtle.write(</span></code> and nothing appears. 530Idle does not itself import turtle. The menu entry and shortcut also do 531nothing. Enter <code class="docutils literal notranslate"><span class="pre">import</span> <span class="pre">turtle</span></code>. Thereafter, <code class="docutils literal notranslate"><span class="pre">turtle.write(</span></code> 532will display a calltip.</p> 533<p>In an editor, import statements have no effect until one runs the file. 534One might want to run a file after writing import statements, after 535adding function definitions, or after opening an existing file.</p> 536</div> 537<div class="section" id="code-context"> 538<span id="id5"></span><h3>Code Context<a class="headerlink" href="#code-context" title="Permalink to this headline">¶</a></h3> 539<p>Within an editor window containing Python code, code context can be toggled 540in order to show or hide a pane at the top of the window. When shown, this 541pane freezes the opening lines for block code, such as those beginning with 542<code class="docutils literal notranslate"><span class="pre">class</span></code>, <code class="docutils literal notranslate"><span class="pre">def</span></code>, or <code class="docutils literal notranslate"><span class="pre">if</span></code> keywords, that would have otherwise scrolled 543out of view. The size of the pane will be expanded and contracted as needed 544to show the all current levels of context, up to the maximum number of 545lines defined in the Configure IDLE dialog (which defaults to 15). If there 546are no current context lines and the feature is toggled on, a single blank 547line will display. Clicking on a line in the context pane will move that 548line to the top of the editor.</p> 549<p>The text and background colors for the context pane can be configured under 550the Highlights tab in the Configure IDLE dialog.</p> 551</div> 552<div class="section" id="python-shell-window"> 553<h3>Python Shell window<a class="headerlink" href="#python-shell-window" title="Permalink to this headline">¶</a></h3> 554<p>With IDLE’s Shell, one enters, edits, and recalls complete statements. 555Most consoles and terminals only work with a single physical line at a time.</p> 556<p>When one pastes code into Shell, it is not compiled and possibly executed 557until one hits <kbd class="kbd docutils literal notranslate">Return</kbd>. One may edit pasted code first. 558If one pastes more that one statement into Shell, the result will be a 559<a class="reference internal" href="exceptions.html#SyntaxError" title="SyntaxError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">SyntaxError</span></code></a> when multiple statements are compiled as if they were one.</p> 560<p>The editing features described in previous subsections work when entering 561code interactively. IDLE’s Shell window also responds to the following keys.</p> 562<ul> 563<li><p><kbd class="kbd docutils literal notranslate"><kbd class="kbd docutils literal notranslate">C</kbd>-<kbd class="kbd docutils literal notranslate">c</kbd></kbd> interrupts executing command</p></li> 564<li><p><kbd class="kbd docutils literal notranslate"><kbd class="kbd docutils literal notranslate">C</kbd>-<kbd class="kbd docutils literal notranslate">d</kbd></kbd> sends end-of-file; closes window if typed at a <code class="docutils literal notranslate"><span class="pre">>>></span></code> prompt</p></li> 565<li><p><kbd class="kbd docutils literal notranslate"><kbd class="kbd docutils literal notranslate">Alt</kbd>-<kbd class="kbd docutils literal notranslate">/</kbd></kbd> (Expand word) is also useful to reduce typing</p> 566<p>Command history</p> 567<ul class="simple"> 568<li><p><kbd class="kbd docutils literal notranslate"><kbd class="kbd docutils literal notranslate">Alt</kbd>-<kbd class="kbd docutils literal notranslate">p</kbd></kbd> retrieves previous command matching what you have typed. On 569macOS use <kbd class="kbd docutils literal notranslate"><kbd class="kbd docutils literal notranslate">C</kbd>-<kbd class="kbd docutils literal notranslate">p</kbd></kbd>.</p></li> 570<li><p><kbd class="kbd docutils literal notranslate"><kbd class="kbd docutils literal notranslate">Alt</kbd>-<kbd class="kbd docutils literal notranslate">n</kbd></kbd> retrieves next. On macOS use <kbd class="kbd docutils literal notranslate"><kbd class="kbd docutils literal notranslate">C</kbd>-<kbd class="kbd docutils literal notranslate">n</kbd></kbd>.</p></li> 571<li><p><kbd class="kbd docutils literal notranslate">Return</kbd> while on any previous command retrieves that command</p></li> 572</ul> 573</li> 574</ul> 575</div> 576<div class="section" id="text-colors"> 577<h3>Text colors<a class="headerlink" href="#text-colors" title="Permalink to this headline">¶</a></h3> 578<p>Idle defaults to black on white text, but colors text with special meanings. 579For the shell, these are shell output, shell error, user output, and 580user error. For Python code, at the shell prompt or in an editor, these are 581keywords, builtin class and function names, names following <code class="docutils literal notranslate"><span class="pre">class</span></code> and 582<code class="docutils literal notranslate"><span class="pre">def</span></code>, strings, and comments. For any text window, these are the cursor (when 583present), found text (when possible), and selected text.</p> 584<p>IDLE also highlights the <a class="reference internal" href="../reference/lexical_analysis.html#soft-keywords"><span class="std std-ref">soft keywords</span></a> <a class="reference internal" href="../reference/compound_stmts.html#match"><code class="xref std std-keyword docutils literal notranslate"><span class="pre">match</span></code></a>, 585<a class="reference internal" href="../reference/compound_stmts.html#match"><code class="xref std std-keyword docutils literal notranslate"><span class="pre">case</span></code></a>, and <a class="reference internal" href="../reference/compound_stmts.html#wildcard-patterns"><code class="xref std std-keyword docutils literal notranslate"><span class="pre">_</span></code></a> in 586pattern-matching statements. However, this highlighting is not perfect and 587will be incorrect in some rare cases, including some <code class="docutils literal notranslate"><span class="pre">_</span></code>-s in <code class="docutils literal notranslate"><span class="pre">case</span></code> 588patterns.</p> 589<p>Text coloring is done in the background, so uncolorized text is occasionally 590visible. To change the color scheme, use the Configure IDLE dialog 591Highlighting tab. The marking of debugger breakpoint lines in the editor and 592text in popups and dialogs is not user-configurable.</p> 593</div> 594</div> 595<div class="section" id="startup-and-code-execution"> 596<h2>Startup and code execution<a class="headerlink" href="#startup-and-code-execution" title="Permalink to this headline">¶</a></h2> 597<p>Upon startup with the <code class="docutils literal notranslate"><span class="pre">-s</span></code> option, IDLE will execute the file referenced by 598the environment variables <span class="target" id="index-5"></span><code class="xref std std-envvar docutils literal notranslate"><span class="pre">IDLESTARTUP</span></code> or <span class="target" id="index-6"></span><a class="reference internal" href="../using/cmdline.html#envvar-PYTHONSTARTUP"><code class="xref std std-envvar docutils literal notranslate"><span class="pre">PYTHONSTARTUP</span></code></a>. 599IDLE first checks for <code class="docutils literal notranslate"><span class="pre">IDLESTARTUP</span></code>; if <code class="docutils literal notranslate"><span class="pre">IDLESTARTUP</span></code> is present the file 600referenced is run. If <code class="docutils literal notranslate"><span class="pre">IDLESTARTUP</span></code> is not present, IDLE checks for 601<code class="docutils literal notranslate"><span class="pre">PYTHONSTARTUP</span></code>. Files referenced by these environment variables are 602convenient places to store functions that are used frequently from the IDLE 603shell, or for executing import statements to import common modules.</p> 604<p>In addition, <code class="docutils literal notranslate"><span class="pre">Tk</span></code> also loads a startup file if it is present. Note that the 605Tk file is loaded unconditionally. This additional file is <code class="docutils literal notranslate"><span class="pre">.Idle.py</span></code> and is 606looked for in the user’s home directory. Statements in this file will be 607executed in the Tk namespace, so this file is not useful for importing 608functions to be used from IDLE’s Python shell.</p> 609<div class="section" id="command-line-usage"> 610<h3>Command line usage<a class="headerlink" href="#command-line-usage" title="Permalink to this headline">¶</a></h3> 611<div class="highlight-none notranslate"><div class="highlight"><pre><span></span>idle.py [-c command] [-d] [-e] [-h] [-i] [-r file] [-s] [-t title] [-] [arg] ... 612 613-c command run command in the shell window 614-d enable debugger and open shell window 615-e open editor window 616-h print help message with legal combinations and exit 617-i open shell window 618-r file run file in shell window 619-s run $IDLESTARTUP or $PYTHONSTARTUP first, in shell window 620-t title set title of shell window 621- run stdin in shell (- must be last option before args) 622</pre></div> 623</div> 624<p>If there are arguments:</p> 625<ul class="simple"> 626<li><p>If <code class="docutils literal notranslate"><span class="pre">-</span></code>, <code class="docutils literal notranslate"><span class="pre">-c</span></code>, or <code class="docutils literal notranslate"><span class="pre">r</span></code> is used, all arguments are placed in 627<code class="docutils literal notranslate"><span class="pre">sys.argv[1:...]</span></code> and <code class="docutils literal notranslate"><span class="pre">sys.argv[0]</span></code> is set to <code class="docutils literal notranslate"><span class="pre">''</span></code>, <code class="docutils literal notranslate"><span class="pre">'-c'</span></code>, 628or <code class="docutils literal notranslate"><span class="pre">'-r'</span></code>. No editor window is opened, even if that is the default 629set in the Options dialog.</p></li> 630<li><p>Otherwise, arguments are files opened for editing and 631<code class="docutils literal notranslate"><span class="pre">sys.argv</span></code> reflects the arguments passed to IDLE itself.</p></li> 632</ul> 633</div> 634<div class="section" id="startup-failure"> 635<h3>Startup failure<a class="headerlink" href="#startup-failure" title="Permalink to this headline">¶</a></h3> 636<p>IDLE uses a socket to communicate between the IDLE GUI process and the user 637code execution process. A connection must be established whenever the Shell 638starts or restarts. (The latter is indicated by a divider line that says 639‘RESTART’). If the user process fails to connect to the GUI process, it 640usually displays a <code class="docutils literal notranslate"><span class="pre">Tk</span></code> error box with a ‘cannot connect’ message 641that directs the user here. It then exits.</p> 642<p>One specific connection failure on Unix systems results from 643misconfigured masquerading rules somewhere in a system’s network setup. 644When IDLE is started from a terminal, one will see a message starting 645with <code class="docutils literal notranslate"><span class="pre">**</span> <span class="pre">Invalid</span> <span class="pre">host:</span></code>. 646The valid value is <code class="docutils literal notranslate"><span class="pre">127.0.0.1</span> <span class="pre">(idlelib.rpc.LOCALHOST)</span></code>. 647One can diagnose with <code class="docutils literal notranslate"><span class="pre">tcpconnect</span> <span class="pre">-irv</span> <span class="pre">127.0.0.1</span> <span class="pre">6543</span></code> in one 648terminal window and <code class="docutils literal notranslate"><span class="pre">tcplisten</span> <span class="pre"><same</span> <span class="pre">args></span></code> in another.</p> 649<p>A common cause of failure is a user-written file with the same name as a 650standard library module, such as <em>random.py</em> and <em>tkinter.py</em>. When such a 651file is located in the same directory as a file that is about to be run, 652IDLE cannot import the stdlib file. The current fix is to rename the 653user file.</p> 654<p>Though less common than in the past, an antivirus or firewall program may 655stop the connection. If the program cannot be taught to allow the 656connection, then it must be turned off for IDLE to work. It is safe to 657allow this internal connection because no data is visible on external 658ports. A similar problem is a network mis-configuration that blocks 659connections.</p> 660<p>Python installation issues occasionally stop IDLE: multiple versions can 661clash, or a single installation might need admin access. If one undo the 662clash, or cannot or does not want to run as admin, it might be easiest to 663completely remove Python and start over.</p> 664<p>A zombie pythonw.exe process could be a problem. On Windows, use Task 665Manager to check for one and stop it if there is. Sometimes a restart 666initiated by a program crash or Keyboard Interrupt (control-C) may fail 667to connect. Dismissing the error box or using Restart Shell on the Shell 668menu may fix a temporary problem.</p> 669<p>When IDLE first starts, it attempts to read user configuration files in 670<code class="docutils literal notranslate"><span class="pre">~/.idlerc/</span></code> (~ is one’s home directory). If there is a problem, an error 671message should be displayed. Leaving aside random disk glitches, this can 672be prevented by never editing the files by hand. Instead, use the 673configuration dialog, under Options. Once there is an error in a user 674configuration file, the best solution may be to delete it and start over 675with the settings dialog.</p> 676<p>If IDLE quits with no message, and it was not started from a console, try 677starting it from a console or terminal (<code class="docutils literal notranslate"><span class="pre">python</span> <span class="pre">-m</span> <span class="pre">idlelib</span></code>) and see if 678this results in an error message.</p> 679<p>On Unix-based systems with tcl/tk older than <code class="docutils literal notranslate"><span class="pre">8.6.11</span></code> (see 680<code class="docutils literal notranslate"><span class="pre">About</span> <span class="pre">IDLE</span></code>) certain characters of certain fonts can cause 681a tk failure with a message to the terminal. This can happen either 682if one starts IDLE to edit a file with such a character or later 683when entering such a character. If one cannot upgrade tcl/tk, 684then re-configure IDLE to use a font that works better.</p> 685</div> 686<div class="section" id="running-user-code"> 687<h3>Running user code<a class="headerlink" href="#running-user-code" title="Permalink to this headline">¶</a></h3> 688<p>With rare exceptions, the result of executing Python code with IDLE is 689intended to be the same as executing the same code by the default method, 690directly with Python in a text-mode system console or terminal window. 691However, the different interface and operation occasionally affect 692visible results. For instance, <code class="docutils literal notranslate"><span class="pre">sys.modules</span></code> starts with more entries, 693and <code class="docutils literal notranslate"><span class="pre">threading.active_count()</span></code> returns 2 instead of 1.</p> 694<p>By default, IDLE runs user code in a separate OS process rather than in 695the user interface process that runs the shell and editor. In the execution 696process, it replaces <code class="docutils literal notranslate"><span class="pre">sys.stdin</span></code>, <code class="docutils literal notranslate"><span class="pre">sys.stdout</span></code>, and <code class="docutils literal notranslate"><span class="pre">sys.stderr</span></code> 697with objects that get input from and send output to the Shell window. 698The original values stored in <code class="docutils literal notranslate"><span class="pre">sys.__stdin__</span></code>, <code class="docutils literal notranslate"><span class="pre">sys.__stdout__</span></code>, and 699<code class="docutils literal notranslate"><span class="pre">sys.__stderr__</span></code> are not touched, but may be <code class="docutils literal notranslate"><span class="pre">None</span></code>.</p> 700<p>Sending print output from one process to a text widget in another is 701slower than printing to a system terminal in the same process. 702This has the most effect when printing multiple arguments, as the string 703for each argument, each separator, the newline are sent separately. 704For development, this is usually not a problem, but if one wants to 705print faster in IDLE, format and join together everything one wants 706displayed together and then print a single string. Both format strings 707and <a class="reference internal" href="stdtypes.html#str.join" title="str.join"><code class="xref py py-meth docutils literal notranslate"><span class="pre">str.join()</span></code></a> can help combine fields and lines.</p> 708<p>IDLE’s standard stream replacements are not inherited by subprocesses 709created in the execution process, whether directly by user code or by 710modules such as multiprocessing. If such subprocess use <code class="docutils literal notranslate"><span class="pre">input</span></code> from 711sys.stdin or <code class="docutils literal notranslate"><span class="pre">print</span></code> or <code class="docutils literal notranslate"><span class="pre">write</span></code> to sys.stdout or sys.stderr, 712IDLE should be started in a command line window. The secondary subprocess 713will then be attached to that window for input and output.</p> 714<p>If <code class="docutils literal notranslate"><span class="pre">sys</span></code> is reset by user code, such as with <code class="docutils literal notranslate"><span class="pre">importlib.reload(sys)</span></code>, 715IDLE’s changes are lost and input from the keyboard and output to the screen 716will not work correctly.</p> 717<p>When Shell has the focus, it controls the keyboard and screen. This is 718normally transparent, but functions that directly access the keyboard 719and screen will not work. These include system-specific functions that 720determine whether a key has been pressed and if so, which.</p> 721<p>The IDLE code running in the execution process adds frames to the call stack 722that would not be there otherwise. IDLE wraps <code class="docutils literal notranslate"><span class="pre">sys.getrecursionlimit</span></code> and 723<code class="docutils literal notranslate"><span class="pre">sys.setrecursionlimit</span></code> to reduce the effect of the additional stack 724frames.</p> 725<p>When user code raises SystemExit either directly or by calling sys.exit, 726IDLE returns to a Shell prompt instead of exiting.</p> 727</div> 728<div class="section" id="user-output-in-shell"> 729<h3>User output in Shell<a class="headerlink" href="#user-output-in-shell" title="Permalink to this headline">¶</a></h3> 730<p>When a program outputs text, the result is determined by the 731corresponding output device. When IDLE executes user code, <code class="docutils literal notranslate"><span class="pre">sys.stdout</span></code> 732and <code class="docutils literal notranslate"><span class="pre">sys.stderr</span></code> are connected to the display area of IDLE’s Shell. Some of 733its features are inherited from the underlying Tk Text widget. Others 734are programmed additions. Where it matters, Shell is designed for development 735rather than production runs.</p> 736<p>For instance, Shell never throws away output. A program that sends unlimited 737output to Shell will eventually fill memory, resulting in a memory error. 738In contrast, some system text windows only keep the last n lines of output. 739A Windows console, for instance, keeps a user-settable 1 to 9999 lines, 740with 300 the default.</p> 741<p>A Tk Text widget, and hence IDLE’s Shell, displays characters (codepoints) in 742the BMP (Basic Multilingual Plane) subset of Unicode. Which characters are 743displayed with a proper glyph and which with a replacement box depends on the 744operating system and installed fonts. Tab characters cause the following text 745to begin after the next tab stop. (They occur every 8 ‘characters’). Newline 746characters cause following text to appear on a new line. Other control 747characters are ignored or displayed as a space, box, or something else, 748depending on the operating system and font. (Moving the text cursor through 749such output with arrow keys may exhibit some surprising spacing behavior.)</p> 750<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="gp">>>> </span><span class="n">s</span> <span class="o">=</span> <span class="s1">'a</span><span class="se">\t</span><span class="s1">b</span><span class="se">\a</span><span class="s1"><</span><span class="se">\x02</span><span class="s1">><</span><span class="se">\r</span><span class="s1">></span><span class="se">\b</span><span class="s1">c</span><span class="se">\n</span><span class="s1">d'</span> <span class="c1"># Enter 22 chars.</span> 751<span class="gp">>>> </span><span class="nb">len</span><span class="p">(</span><span class="n">s</span><span class="p">)</span> 752<span class="go">14</span> 753<span class="gp">>>> </span><span class="n">s</span> <span class="c1"># Display repr(s)</span> 754<span class="go">'a\tb\x07<\x02><\r>\x08c\nd'</span> 755<span class="gp">>>> </span><span class="nb">print</span><span class="p">(</span><span class="n">s</span><span class="p">,</span> <span class="n">end</span><span class="o">=</span><span class="s1">''</span><span class="p">)</span> <span class="c1"># Display s as is.</span> 756<span class="go"># Result varies by OS and font. Try it.</span> 757</pre></div> 758</div> 759<p>The <code class="docutils literal notranslate"><span class="pre">repr</span></code> function is used for interactive echo of expression 760values. It returns an altered version of the input string in which 761control codes, some BMP codepoints, and all non-BMP codepoints are 762replaced with escape codes. As demonstrated above, it allows one to 763identify the characters in a string, regardless of how they are displayed.</p> 764<p>Normal and error output are generally kept separate (on separate lines) 765from code input and each other. They each get different highlight colors.</p> 766<p>For SyntaxError tracebacks, the normal ‘^’ marking where the error was 767detected is replaced by coloring the text with an error highlight. 768When code run from a file causes other exceptions, one may right click 769on a traceback line to jump to the corresponding line in an IDLE editor. 770The file will be opened if necessary.</p> 771<p>Shell has a special facility for squeezing output lines down to a 772‘Squeezed text’ label. This is done automatically 773for output over N lines (N = 50 by default). 774N can be changed in the PyShell section of the General 775page of the Settings dialog. Output with fewer lines can be squeezed by 776right clicking on the output. This can be useful lines long enough to slow 777down scrolling.</p> 778<p>Squeezed output is expanded in place by double-clicking the label. 779It can also be sent to the clipboard or a separate view window by 780right-clicking the label.</p> 781</div> 782<div class="section" id="developing-tkinter-applications"> 783<h3>Developing tkinter applications<a class="headerlink" href="#developing-tkinter-applications" title="Permalink to this headline">¶</a></h3> 784<p>IDLE is intentionally different from standard Python in order to 785facilitate development of tkinter programs. Enter <code class="docutils literal notranslate"><span class="pre">import</span> <span class="pre">tkinter</span> <span class="pre">as</span> <span class="pre">tk;</span> 786<span class="pre">root</span> <span class="pre">=</span> <span class="pre">tk.Tk()</span></code> in standard Python and nothing appears. Enter the same 787in IDLE and a tk window appears. In standard Python, one must also enter 788<code class="docutils literal notranslate"><span class="pre">root.update()</span></code> to see the window. IDLE does the equivalent in the 789background, about 20 times a second, which is about every 50 milliseconds. 790Next enter <code class="docutils literal notranslate"><span class="pre">b</span> <span class="pre">=</span> <span class="pre">tk.Button(root,</span> <span class="pre">text='button');</span> <span class="pre">b.pack()</span></code>. Again, 791nothing visibly changes in standard Python until one enters <code class="docutils literal notranslate"><span class="pre">root.update()</span></code>.</p> 792<p>Most tkinter programs run <code class="docutils literal notranslate"><span class="pre">root.mainloop()</span></code>, which usually does not 793return until the tk app is destroyed. If the program is run with 794<code class="docutils literal notranslate"><span class="pre">python</span> <span class="pre">-i</span></code> or from an IDLE editor, a <code class="docutils literal notranslate"><span class="pre">>>></span></code> shell prompt does not 795appear until <code class="docutils literal notranslate"><span class="pre">mainloop()</span></code> returns, at which time there is nothing left 796to interact with.</p> 797<p>When running a tkinter program from an IDLE editor, one can comment out 798the mainloop call. One then gets a shell prompt immediately and can 799interact with the live application. One just has to remember to 800re-enable the mainloop call when running in standard Python.</p> 801</div> 802<div class="section" id="running-without-a-subprocess"> 803<h3>Running without a subprocess<a class="headerlink" href="#running-without-a-subprocess" title="Permalink to this headline">¶</a></h3> 804<p>By default, IDLE executes user code in a separate subprocess via a socket, 805which uses the internal loopback interface. This connection is not 806externally visible and no data is sent to or received from the internet. 807If firewall software complains anyway, you can ignore it.</p> 808<p>If the attempt to make the socket connection fails, Idle will notify you. 809Such failures are sometimes transient, but if persistent, the problem 810may be either a firewall blocking the connection or misconfiguration of 811a particular system. Until the problem is fixed, one can run Idle with 812the -n command line switch.</p> 813<p>If IDLE is started with the -n command line switch it will run in a 814single process and will not create the subprocess which runs the RPC 815Python execution server. This can be useful if Python cannot create 816the subprocess or the RPC socket interface on your platform. However, 817in this mode user code is not isolated from IDLE itself. Also, the 818environment is not restarted when Run/Run Module (F5) is selected. If 819your code has been modified, you must reload() the affected modules and 820re-import any specific items (e.g. from foo import baz) if the changes 821are to take effect. For these reasons, it is preferable to run IDLE 822with the default subprocess if at all possible.</p> 823<div class="deprecated"> 824<p><span class="versionmodified deprecated">Deprecated since version 3.4.</span></p> 825</div> 826</div> 827</div> 828<div class="section" id="help-and-preferences"> 829<h2>Help and preferences<a class="headerlink" href="#help-and-preferences" title="Permalink to this headline">¶</a></h2> 830<div class="section" id="help-sources"> 831<span id="id6"></span><h3>Help sources<a class="headerlink" href="#help-sources" title="Permalink to this headline">¶</a></h3> 832<p>Help menu entry “IDLE Help” displays a formatted html version of the 833IDLE chapter of the Library Reference. The result, in a read-only 834tkinter text window, is close to what one sees in a web browser. 835Navigate through the text with a mousewheel, 836the scrollbar, or up and down arrow keys held down. 837Or click the TOC (Table of Contents) button and select a section 838header in the opened box.</p> 839<p>Help menu entry “Python Docs” opens the extensive sources of help, 840including tutorials, available at <code class="docutils literal notranslate"><span class="pre">docs.python.org/x.y</span></code>, where ‘x.y’ 841is the currently running Python version. If your system 842has an off-line copy of the docs (this may be an installation option), 843that will be opened instead.</p> 844<p>Selected URLs can be added or removed from the help menu at any time using the 845General tab of the Configure IDLE dialog.</p> 846</div> 847<div class="section" id="setting-preferences"> 848<span id="preferences"></span><h3>Setting preferences<a class="headerlink" href="#setting-preferences" title="Permalink to this headline">¶</a></h3> 849<p>The font preferences, highlighting, keys, and general preferences can be 850changed via Configure IDLE on the Option menu. 851Non-default user settings are saved in a <code class="docutils literal notranslate"><span class="pre">.idlerc</span></code> directory in the user’s 852home directory. Problems caused by bad user configuration files are solved 853by editing or deleting one or more of the files in <code class="docutils literal notranslate"><span class="pre">.idlerc</span></code>.</p> 854<p>On the Font tab, see the text sample for the effect of font face and size 855on multiple characters in multiple languages. Edit the sample to add 856other characters of personal interest. Use the sample to select 857monospaced fonts. If particular characters have problems in Shell or an 858editor, add them to the top of the sample and try changing first size 859and then font.</p> 860<p>On the Highlights and Keys tab, select a built-in or custom color theme 861and key set. To use a newer built-in color theme or key set with older 862IDLEs, save it as a new custom theme or key set and it well be accessible 863to older IDLEs.</p> 864</div> 865<div class="section" id="idle-on-macos"> 866<h3>IDLE on macOS<a class="headerlink" href="#idle-on-macos" title="Permalink to this headline">¶</a></h3> 867<p>Under System Preferences: Dock, one can set “Prefer tabs when opening 868documents” to “Always”. This setting is not compatible with the tk/tkinter 869GUI framework used by IDLE, and it breaks a few IDLE features.</p> 870</div> 871<div class="section" id="extensions"> 872<h3>Extensions<a class="headerlink" href="#extensions" title="Permalink to this headline">¶</a></h3> 873<p>IDLE contains an extension facility. Preferences for extensions can be 874changed with the Extensions tab of the preferences dialog. See the 875beginning of config-extensions.def in the idlelib directory for further 876information. The only current default extension is zzdummy, an example 877also used for testing.</p> 878</div> 879</div> 880</div> 881 882 883 <div class="clearer"></div> 884 </div> 885 </div> 886 </div> 887 <div class="sphinxsidebar" role="navigation" aria-label="main navigation"> 888 <div class="sphinxsidebarwrapper"> 889 <h3><a href="../contents.html">Table of Contents</a></h3> 890 <ul> 891<li><a class="reference internal" href="#">IDLE</a><ul> 892<li><a class="reference internal" href="#menus">Menus</a><ul> 893<li><a class="reference internal" href="#file-menu-shell-and-editor">File menu (Shell and Editor)</a></li> 894<li><a class="reference internal" href="#edit-menu-shell-and-editor">Edit menu (Shell and Editor)</a></li> 895<li><a class="reference internal" href="#format-menu-editor-window-only">Format menu (Editor window only)</a></li> 896<li><a class="reference internal" href="#run-menu-editor-window-only">Run menu (Editor window only)</a></li> 897<li><a class="reference internal" href="#shell-menu-shell-window-only">Shell menu (Shell window only)</a></li> 898<li><a class="reference internal" href="#debug-menu-shell-window-only">Debug menu (Shell window only)</a></li> 899<li><a class="reference internal" href="#options-menu-shell-and-editor">Options menu (Shell and Editor)</a></li> 900<li><a class="reference internal" href="#window-menu-shell-and-editor">Window menu (Shell and Editor)</a></li> 901<li><a class="reference internal" href="#help-menu-shell-and-editor">Help menu (Shell and Editor)</a></li> 902<li><a class="reference internal" href="#context-menus">Context Menus</a></li> 903</ul> 904</li> 905<li><a class="reference internal" href="#editing-and-navigation">Editing and navigation</a><ul> 906<li><a class="reference internal" href="#editor-windows">Editor windows</a></li> 907<li><a class="reference internal" href="#key-bindings">Key bindings</a></li> 908<li><a class="reference internal" href="#automatic-indentation">Automatic indentation</a></li> 909<li><a class="reference internal" href="#completions">Completions</a></li> 910<li><a class="reference internal" href="#calltips">Calltips</a></li> 911<li><a class="reference internal" href="#code-context">Code Context</a></li> 912<li><a class="reference internal" href="#python-shell-window">Python Shell window</a></li> 913<li><a class="reference internal" href="#text-colors">Text colors</a></li> 914</ul> 915</li> 916<li><a class="reference internal" href="#startup-and-code-execution">Startup and code execution</a><ul> 917<li><a class="reference internal" href="#command-line-usage">Command line usage</a></li> 918<li><a class="reference internal" href="#startup-failure">Startup failure</a></li> 919<li><a class="reference internal" href="#running-user-code">Running user code</a></li> 920<li><a class="reference internal" href="#user-output-in-shell">User output in Shell</a></li> 921<li><a class="reference internal" href="#developing-tkinter-applications">Developing tkinter applications</a></li> 922<li><a class="reference internal" href="#running-without-a-subprocess">Running without a subprocess</a></li> 923</ul> 924</li> 925<li><a class="reference internal" href="#help-and-preferences">Help and preferences</a><ul> 926<li><a class="reference internal" href="#help-sources">Help sources</a></li> 927<li><a class="reference internal" href="#setting-preferences">Setting preferences</a></li> 928<li><a class="reference internal" href="#idle-on-macos">IDLE on macOS</a></li> 929<li><a class="reference internal" href="#extensions">Extensions</a></li> 930</ul> 931</li> 932</ul> 933</li> 934</ul> 935 936 <h4>Previous topic</h4> 937 <p class="topless"><a href="tkinter.tix.html" 938 title="previous chapter"><code class="xref py py-mod docutils literal notranslate"><span class="pre">tkinter.tix</span></code> — Extension widgets for Tk</a></p> 939 <h4>Next topic</h4> 940 <p class="topless"><a href="development.html" 941 title="next chapter">Development Tools</a></p> 942 <div role="note" aria-label="source link"> 943 <h3>This Page</h3> 944 <ul class="this-page-menu"> 945 <li><a href="../bugs.html">Report a Bug</a></li> 946 <li> 947 <a href="https://github.com/python/cpython/blob/main/Doc/library/idle.rst" 948 rel="nofollow">Show Source 949 </a> 950 </li> 951 </ul> 952 </div> 953 </div> 954 </div> 955 <div class="clearer"></div> 956 </div> 957 <div class="related" role="navigation" aria-label="related navigation"> 958 <h3>Navigation</h3> 959 <ul> 960 <li class="right" style="margin-right: 10px"> 961 <a href="../genindex.html" title="General Index" 962 >index</a></li> 963 <li class="right" > 964 <a href="../py-modindex.html" title="Python Module Index" 965 >modules</a> |</li> 966 <li class="right" > 967 <a href="development.html" title="Development Tools" 968 >next</a> |</li> 969 <li class="right" > 970 <a href="tkinter.tix.html" title="tkinter.tix — Extension widgets for Tk" 971 >previous</a> |</li> 972 973 <li><img src="../_static/py.png" alt="" 974 style="vertical-align: middle; 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