<section id="idle">

<span id="idle-python-editor-and-shell"></span><h1>IDLE — Python editor and shell<a class="headerlink" href="#idle" title="Link to this heading">¶</a></h1>

<p><strong>Source code:</strong> <a class="extlink-source reference external" href="https://github.com/python/cpython/tree/main/Lib/idlelib/">Lib/idlelib/</a></p>

<span class="target" id="index-0"></span><hr class="docutils" />

<p>IDLE is Python’s Integrated Development and Learning Environment.</p>

<p>IDLE has the following features:</p>

<ul class="simple">

<li><p>cross-platform: works mostly the same on Windows, Unix, and macOS</p></li>

<li><p>Python shell window (interactive interpreter) with colorizing

of code input, output, and error messages</p></li>

<li><p>multi-window text editor with multiple undo, Python colorizing,

smart indent, call tips, auto completion, and other features</p></li>

<li><p>search within any window, replace within editor windows, and search

through multiple files (grep)</p></li>

<li><p>debugger with persistent breakpoints, stepping, and viewing

of global and local namespaces</p></li>

<li><p>configuration, browsers, and other dialogs</p></li>

</ul>

<p>The IDLE application is implemented in the <a class="reference internal" href="#module-idlelib" title="idlelib: Implementation package for the IDLE shell/editor."><code class="xref py py-mod docutils literal notranslate"><span class="pre">idlelib</span></code></a> package.</p>

<p>This is an <a class="reference internal" href="../glossary.html#term-optional-module"><span class="xref std std-term">optional module</span></a>.

If it is missing from your copy of CPython,

look for documentation from your distributor (that is,

whoever provided Python to you).

If you are the distributor, see <a class="reference internal" href="../using/configure.html#optional-module-requirements"><span class="std std-ref">Requirements for optional modules</span></a>.</p>

<section id="menus">

<h2>Menus<a class="headerlink" href="#menus" title="Link to this heading">¶</a></h2>

<p>IDLE has two main window types, the Shell window and the Editor window. It is

possible to have multiple editor windows simultaneously. On Windows and

Linux, each has its own top menu. Each menu documented below indicates

which window type it is associated with.</p>

<p>Output windows, such as used for Edit =&gt; Find in Files, are a subtype of editor

window. They currently have the same top menu but a different

default title and context menu.</p>

<p>On macOS, there is one application menu. It dynamically changes according

to the window currently selected. It has an IDLE menu, and some entries

described below are moved around to conform to Apple guidelines.</p>

<section id="file-menu-shell-and-editor">

<h3>File menu (Shell and Editor)<a class="headerlink" href="#file-menu-shell-and-editor" title="Link to this heading">¶</a></h3>

<dl class="simple">

<dt>New File</dt><dd><p>Create a new file editing window.</p>

</dd>

<dt>Open…</dt><dd><p>Open an existing file with an Open dialog.</p>

</dd>

<dt>Open Module…</dt><dd><p>Open an existing module (searches sys.path).</p>

</dd>

<dt>Recent Files</dt><dd><p>Open a list of recent files. Click one to open it.</p>

</dd>

</dl>

<dl class="simple" id="index-1">

<dt>Module Browser</dt><dd><p>Show functions, classes, and methods in the current Editor file in a

tree structure. In the shell, open a module first.</p>

</dd>

<dt>Path Browser</dt><dd><p>Show sys.path directories, modules, functions, classes and methods in a

tree structure.</p>

</dd>

<dt>Save</dt><dd><p>Save the current window to the associated file, if there is one. Windows

that have been changed since being opened or last saved have a * before

and after the window title. If there is no associated file,

do Save As instead.</p>

</dd>

<dt>Save As…</dt><dd><p>Save the current window with a Save As dialog. The file saved becomes the

new associated file for the window. (If your file manager is set to hide

extensions, the current extension will be omitted in the file name box.

If the new filename has no ‘.’, ‘.py’ and ‘.txt’ will be added for Python

and text files, except that on macOS Aqua,’.py’ is added for all files.)</p>

</dd>

<dt>Save Copy As…</dt><dd><p>Save the current window to different file without changing the associated

file. (See Save As note above about filename extensions.)</p>

</dd>

<dt>Print Window</dt><dd><p>Print the current window to the default printer.</p>

</dd>

<dt>Close Window</dt><dd><p>Close the current window (if an unsaved editor, ask to save; if an unsaved

Shell, ask to quit execution). Calling <code class="docutils literal notranslate"><span class="pre">exit()</span></code> or <code class="docutils literal notranslate"><span class="pre">close()</span></code> in the Shell

window also closes Shell. If this is the only window, also exit IDLE.</p>

</dd>

<dt>Exit IDLE</dt><dd><p>Close all windows and quit IDLE (ask to save unsaved edit windows).</p>

</dd>

</dl>

</section>

<section id="edit-menu-shell-and-editor">

<h3>Edit menu (Shell and Editor)<a class="headerlink" href="#edit-menu-shell-and-editor" title="Link to this heading">¶</a></h3>

<dl class="simple">

<dt>Undo</dt><dd><p>Undo the last change to the current window. A maximum of 1000 changes may

be undone.</p>

</dd>

<dt>Redo</dt><dd><p>Redo the last undone change to the current window.</p>

</dd>

<dt>Select All</dt><dd><p>Select the entire contents of the current window.</p>

</dd>

<dt>Cut</dt><dd><p>Copy selection into the system-wide clipboard; then delete the selection.</p>

</dd>

<dt>Copy</dt><dd><p>Copy selection into the system-wide clipboard.</p>

</dd>

<dt>Paste</dt><dd><p>Insert contents of the system-wide clipboard into the current window.</p>

</dd>

</dl>

<p>The clipboard functions are also available in context menus.</p>

<dl class="simple">

<dt>Find…</dt><dd><p>Open a search dialog with many options</p>

</dd>

<dt>Find Again</dt><dd><p>Repeat the last search, if there is one.</p>

</dd>

<dt>Find Selection</dt><dd><p>Search for the currently selected string, if there is one.</p>

</dd>

<dt>Find in Files…</dt><dd><p>Open a file search dialog. Put results in a new output window.</p>

</dd>

<dt>Replace…</dt><dd><p>Open a search-and-replace dialog.</p>

</dd>

<dt>Go to Line</dt><dd><p>Move the cursor to the beginning of the line requested and make that

line visible. A request past the end of the file goes to the end.

Clear any selection and update the line and column status.</p>

</dd>

<dt>Show Completions</dt><dd><p>Open a scrollable list allowing selection of existing names. See

<a class="reference internal" href="#completions"><span class="std std-ref">Completions</span></a> in the Editing and Navigation section below.</p>

</dd>

<dt>Expand Word</dt><dd><p>Expand a prefix you have typed to match a full word in the same window;

repeat to get a different expansion.</p>

</dd>

<dt>Show Call Tip</dt><dd><p>After an unclosed parenthesis for a function, open a small window with

function parameter hints. See <a class="reference internal" href="#calltips"><span class="std std-ref">Calltips</span></a> in the

Editing and Navigation section below.</p>

</dd>

<dt>Show Surrounding Parens</dt><dd><p>Highlight the surrounding parenthesis.</p>

</dd>

</dl>

</section>

<section id="format-menu-editor-window-only">

<span id="format-menu"></span><h3>Format menu (Editor window only)<a class="headerlink" href="#format-menu-editor-window-only" title="Link to this heading">¶</a></h3>

<dl class="simple">

<dt>Format Paragraph</dt><dd><p>Rewrap the text block containing the text insert cursor.

Avoid code lines. See <a class="reference internal" href="#format-block"><span class="std std-ref">Format block</span></a> in the

Editing and Navigation section below.</p>

</dd>

<dt>Indent Region</dt><dd><p>Shift selected lines right by the indent width (default 4 spaces).</p>

</dd>

<dt>Dedent Region</dt><dd><p>Shift selected lines left by the indent width (default 4 spaces).</p>

</dd>

<dt>Comment Out Region</dt><dd><p>Insert ## in front of selected lines.</p>

</dd>

<dt>Uncomment Region</dt><dd><p>Remove leading # or ## from selected lines.</p>

</dd>

<dt>Tabify Region</dt><dd><p>Turn <em>leading</em> stretches of spaces into tabs. (Note: We recommend using

4 space blocks to indent Python code.)</p>

</dd>

<dt>Untabify Region</dt><dd><p>Turn <em>all</em> tabs into the correct number of spaces.</p>

</dd>

<dt>Toggle Tabs</dt><dd><p>Open a dialog to switch between indenting with spaces and tabs.</p>

</dd>

<dt>New Indent Width</dt><dd><p>Open a dialog to change indent width. The accepted default by the Python

community is 4 spaces.</p>

</dd>

<dt>Strip Trailing Whitespace</dt><dd><p>Remove trailing space and other whitespace characters after the last

non-whitespace character of a line by applying <a class="reference internal" href="stdtypes.html#str.rstrip" title="str.rstrip"><code class="xref py py-meth docutils literal notranslate"><span class="pre">str.rstrip()</span></code></a> to each line,

including lines within multiline strings. Except for Shell windows,

remove extra newlines at the end of the file.</p>

</dd>

</dl>

</section>

<section id="run-menu-editor-window-only">

<span id="index-2"></span><h3>Run menu (Editor window only)<a class="headerlink" href="#run-menu-editor-window-only" title="Link to this heading">¶</a></h3>

<dl class="simple" id="run-module">

<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

environment, then execute the module. Output is displayed in the Shell

window. 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>.

When execution is complete, the Shell retains focus and displays a prompt.

At this point, one may interactively explore the result of execution.

This 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

line.</p>

</dd>

</dl>

<dl class="simple" id="run-custom">

<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

settings. <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

on a command line. The module can be run in the Shell without restarting.</p>

</dd>

</dl>

<dl class="simple" id="check-module">

<dt>Check Module</dt><dd><p>Check the syntax of the module currently open in the Editor window. If the

module has not been saved IDLE will either prompt the user to save or

autosave, as selected in the General tab of the Idle Settings dialog. If

there is a syntax error, the approximate location is indicated in the

Editor window.</p>

</dd>

</dl>

<dl class="simple" id="python-shell">

<dt>Python Shell</dt><dd><p>Open or wake up the Python Shell window.</p>

</dd>

</dl>

</section>

<section id="shell-menu-shell-window-only">

<h3>Shell menu (Shell window only)<a class="headerlink" href="#shell-menu-shell-window-only" title="Link to this heading">¶</a></h3>

<dl class="simple">

<dt>View Last Restart</dt><dd><p>Scroll the shell window to the last Shell restart.</p>

</dd>

<dt>Restart Shell</dt><dd><p>Restart the shell to clean the environment and reset display and exception handling.</p>

</dd>

<dt>Previous History</dt><dd><p>Cycle through earlier commands in history which match the current entry.</p>

</dd>

<dt>Next History</dt><dd><p>Cycle through later commands in history which match the current entry.</p>

</dd>

<dt>Interrupt Execution</dt><dd><p>Stop a running program.</p>

</dd>

</dl>

</section>

<section id="debug-menu-shell-window-only">

<h3>Debug menu (Shell window only)<a class="headerlink" href="#debug-menu-shell-window-only" title="Link to this heading">¶</a></h3>

<dl class="simple">

<dt>Go to File/Line</dt><dd><p>Look on the current line. with the cursor, and the line above for a filename

and line number. If found, open the file if not already open, and show the

line. Use this to view source lines referenced in an exception traceback

and lines found by Find in Files. Also available in the context menu of

the Shell window and Output windows.</p>

</dd>

</dl>

<dl class="simple" id="index-3">

<dt>Debugger (toggle)</dt><dd><p>When activated, code entered in the Shell or run from an Editor will run

under the debugger. In the Editor, breakpoints can be set with the context

menu. This feature is still incomplete and somewhat experimental.</p>

</dd>

<dt>Stack Viewer</dt><dd><p>Show the stack traceback of the last exception in a tree widget, with

access to locals and globals.</p>

</dd>

<dt>Auto-open Stack Viewer</dt><dd><p>Toggle automatically opening the stack viewer on an unhandled exception.</p>

</dd>

</dl>

</section>

<section id="options-menu-shell-and-editor">

<h3>Options menu (Shell and Editor)<a class="headerlink" href="#options-menu-shell-and-editor" title="Link to this heading">¶</a></h3>

<dl class="simple">

<dt>Configure IDLE</dt><dd><p>Open a configuration dialog and change preferences for the following:

fonts, indentation, keybindings, text color themes, startup windows and

size, additional help sources, and extensions. On macOS, open the

configuration dialog by selecting Preferences in the application

menu. For more details, see

<a class="reference internal" href="#preferences"><span class="std std-ref">Setting preferences</span></a> under Help and preferences.</p>

</dd>

</dl>

<p>Most configuration options apply to all windows or all future windows.

The option items below only apply to the active window.</p>

<dl class="simple">

<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

of the code which has scrolled above the top of the window. See

<a class="reference internal" href="#code-context"><span class="std std-ref">Code Context</span></a> in the Editing and Navigation section

below.</p>

</dd>

<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

of each line of text. The default is off, which may be changed in the

preferences (see <a class="reference internal" href="#preferences"><span class="std std-ref">Setting preferences</span></a>).</p>

</dd>

<dt>Zoom/Restore Height</dt><dd><p>Toggles the window between normal size and maximum height. The initial size

defaults to 40 lines by 80 chars unless changed on the General tab of the

Configure IDLE dialog. The maximum height for a screen is determined by

momentarily maximizing a window the first time one is zoomed on the screen.

Changing screen settings may invalidate the saved height. This toggle has

no effect when a window is maximized.</p>

</dd>

</dl>

</section>

<section id="window-menu-shell-and-editor">

<h3>Window menu (Shell and Editor)<a class="headerlink" href="#window-menu-shell-and-editor" title="Link to this heading">¶</a></h3>

<p>Lists the names of all open windows; select one to bring it to the foreground

(deiconifying it if necessary).</p>

</section>

<section id="help-menu-shell-and-editor">

<h3>Help menu (Shell and Editor)<a class="headerlink" href="#help-menu-shell-and-editor" title="Link to this heading">¶</a></h3>

<dl class="simple">

<dt>About IDLE</dt><dd><p>Display version, copyright, license, credits, and more.</p>

</dd>

<dt>IDLE Help</dt><dd><p>Display this IDLE document, detailing the menu options, basic editing and

navigation, and other tips.</p>

</dd>

<dt>Python Docs</dt><dd><p>Access local Python documentation, if installed, or start a web browser

and open docs.python.org showing the latest Python documentation.</p>

</dd>

<dt>Turtle Demo</dt><dd><p>Run the turtledemo module with example Python code and turtle drawings.</p>

</dd>

</dl>

<p>Additional help sources may be added here with the Configure IDLE dialog under

the General tab. See the <a class="reference internal" href="#help-sources"><span class="std std-ref">Help sources</span></a> subsection below

for more on Help menu choices.</p>

</section>

<section id="context-menus">

<span id="index-4"></span><h3>Context menus<a class="headerlink" href="#context-menus" title="Link to this heading">¶</a></h3>

<p>Open a context menu by right-clicking in a window (Control-click on macOS).

Context menus have the standard clipboard functions also on the Edit menu.</p>

<dl class="simple">

<dt>Cut</dt><dd><p>Copy selection into the system-wide clipboard; then delete the selection.</p>

</dd>

<dt>Copy</dt><dd><p>Copy selection into the system-wide clipboard.</p>

</dd>

<dt>Paste</dt><dd><p>Insert contents of the system-wide clipboard into the current window.</p>

</dd>

</dl>

<p>Editor windows also have breakpoint functions. Lines with a breakpoint set are

specially marked. Breakpoints only have an effect when running under the

debugger. Breakpoints for a file are saved in the user’s <code class="docutils literal notranslate"><span class="pre">.idlerc</span></code>

directory.</p>

<dl class="simple">

<dt>Set Breakpoint</dt><dd><p>Set a breakpoint on the current line.</p>

</dd>

<dt>Clear Breakpoint</dt><dd><p>Clear the breakpoint on that line.</p>

</dd>

</dl>

<p>Shell and Output windows also have the following.</p>

<dl class="simple">

<dt>Go to file/line</dt><dd><p>Same as in Debug menu.</p>

</dd>

</dl>

<p>The Shell window also has an output squeezing facility explained in the <em>Python

Shell window</em> subsection below.</p>

<dl class="simple">

<dt>Squeeze</dt><dd><p>If the cursor is over an output line, squeeze all the output between

the code above and the prompt below down to a ‘Squeezed text’ label.</p>

</dd>

</dl>

</section>

</section>

<section id="editing-and-navigation">

<span id="id1"></span><h2>Editing and Navigation<a class="headerlink" href="#editing-and-navigation" title="Link to this heading">¶</a></h2>

<section id="editor-windows">

<h3>Editor windows<a class="headerlink" href="#editor-windows" title="Link to this heading">¶</a></h3>

<p>IDLE may open editor windows when it starts, depending on settings

and how you start IDLE. Thereafter, use the File menu. There can be only

one open editor window for a given file.</p>

<p>The title bar contains the name of the file, the full path, and the version

of Python and IDLE running the window. The status bar contains the line

number (‘Ln’) and column number (‘Col’). Line numbers start with 1;

column numbers with 0.</p>

<p>IDLE assumes that files with a known .py* extension contain Python code

and that other files do not. Run Python code with the Run menu.</p>

</section>

<section id="key-bindings">

<h3>Key bindings<a class="headerlink" href="#key-bindings" title="Link to this heading">¶</a></h3>

<p>The IDLE insertion cursor is a thin vertical bar between character

positions. When characters are entered, the insertion cursor and

everything to its right moves right one character and

the new character is entered in the new space.</p>

<p>Several non-character keys move the cursor and possibly

delete characters. Deletion does not puts text on the clipboard,

but IDLE has an undo list. Wherever this doc discusses keys,

‘C’ refers to the <kbd class="kbd docutils literal notranslate">Control</kbd> key on Windows and

Unix and the <kbd class="kbd docutils literal notranslate">Command</kbd> key on macOS. (And all such discussions

assume that the keys have not been re-bound to something else.)</p>

<ul class="simple">

<li><p>Arrow keys move the cursor one character or line.</p></li>

<li><p><kbd class="kbd docutils literal notranslate">C</kbd>-<kbd class="kbd docutils literal notranslate">LeftArrow</kbd> and <kbd class="kbd docutils literal notranslate">C</kbd>-<kbd class="kbd docutils literal notranslate">RightArrow</kbd> moves left or right one word.</p></li>

<li><p><kbd class="kbd docutils literal notranslate">Home</kbd> and <kbd class="kbd docutils literal notranslate">End</kbd> go to the beginning or end of the line.</p></li>

<li><p><kbd class="kbd docutils literal notranslate">Page Up</kbd> and <kbd class="kbd docutils literal notranslate">Page Down</kbd> go up or down one screen.</p></li>

<li><p><kbd class="kbd docutils literal notranslate">C</kbd>-<kbd class="kbd docutils literal notranslate">Home</kbd> and <kbd class="kbd docutils literal notranslate">C</kbd>-<kbd class="kbd docutils literal notranslate">End</kbd> go to beginning or end of the file.</p></li>

<li><p><kbd class="kbd docutils literal notranslate">Backspace</kbd> and <kbd class="kbd docutils literal notranslate">Del</kbd> (or <kbd class="kbd docutils literal notranslate">C</kbd>-<kbd class="kbd docutils literal notranslate">d</kbd>) delete the previous

or next character.</p></li>

<li><p><kbd class="kbd docutils literal notranslate">C</kbd>-<kbd class="kbd docutils literal notranslate">Backspace</kbd> and <kbd class="kbd docutils literal notranslate">C</kbd>-<kbd class="kbd docutils literal notranslate">Del</kbd> delete one word left or right.</p></li>

<li><p><kbd class="kbd docutils literal notranslate">C</kbd>-<kbd class="kbd docutils literal notranslate">k</kbd> deletes (‘kills’) everything to the right.</p></li>

</ul>

<p>Standard keybindings (like <kbd class="kbd docutils literal notranslate">C</kbd>-<kbd class="kbd docutils literal notranslate">c</kbd> to copy and <kbd class="kbd docutils literal notranslate">C</kbd>-<kbd class="kbd docutils literal notranslate">v</kbd> to paste)

may work. Keybindings are selected in the Configure IDLE dialog.</p>

</section>

<section id="automatic-indentation">

<h3>Automatic indentation<a class="headerlink" href="#automatic-indentation" title="Link to this heading">¶</a></h3>

<p>After a block-opening statement, the next line is indented by 4 spaces (in the

Python Shell window by one tab). After certain keywords (break, return etc.)

the next line is dedented. In leading indentation, <kbd class="kbd docutils literal notranslate">Backspace</kbd> deletes up

to 4 spaces if they are there. <kbd class="kbd docutils literal notranslate">Tab</kbd> inserts spaces (in the Python

Shell window one tab), number depends on Indent width. Currently, tabs

are restricted to four spaces due to Tcl/Tk limitations.</p>

<p>See also the indent/dedent region commands on the

<a class="reference internal" href="#format-menu"><span class="std std-ref">Format menu</span></a>.</p>

</section>

<section id="search-and-replace">

<h3>Search and Replace<a class="headerlink" href="#search-and-replace" title="Link to this heading">¶</a></h3>

<p>Any selection becomes a search target. However, only selections within

a line work because searches are only performed within lines with the

terminal newline removed. If <code class="docutils literal notranslate"><span class="pre">[x]</span> <span class="pre">Regular</span> <span class="pre">expression</span></code> is checked, the

target is interpreted according to the Python re module.</p>

</section>

<section id="completions">

<span id="id2"></span><h3>Completions<a class="headerlink" href="#completions" title="Link to this heading">¶</a></h3>

<p>Completions are supplied, when requested and available, for module

names, attributes of classes or functions, or filenames. Each request

method displays a completion box with existing names. (See tab

completions below for an exception.) For any box, change the name

being completed and the item highlighted in the box by

typing and deleting characters; by hitting <kbd class="kbd docutils literal notranslate">Up</kbd>, <kbd class="kbd docutils literal notranslate">Down</kbd>,

<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;

and by a single click within the box. Close the box with <kbd class="kbd docutils literal notranslate">Escape</kbd>,

<kbd class="kbd docutils literal notranslate">Enter</kbd>, and double <kbd class="kbd docutils literal notranslate">Tab</kbd> keys or clicks outside the box.

A double click within the box selects and closes.</p>

<p>One way to open a box is to type a key character and wait for a

predefined interval. This defaults to 2 seconds; customize it

in the settings dialog. (To prevent auto popups, set the delay to a

large number of milliseconds, such as 100000000.) For imported module

names or class or function attributes, type ‘.’.

For 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

<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,

one can specify a drive first.) Move into subdirectories by typing a

directory name and a separator.</p>

<p>Instead of waiting, or after a box is closed, open a completion box

immediately with Show Completions on the Edit menu. The default hot

key is <kbd class="kbd docutils literal notranslate">C</kbd>-<kbd class="kbd docutils literal notranslate">space</kbd>. If one types a prefix for the desired name

before opening the box, the first match or near miss is made visible.

The result is the same as if one enters a prefix

after the box is displayed. Show Completions after a quote completes

filenames in the current directory instead of a root directory.</p>

<p>Hitting <kbd class="kbd docutils literal notranslate">Tab</kbd> after a prefix usually has the same effect as Show

Completions. (With no prefix, it indents.) However, if there is only

one match to the prefix, that match is immediately added to the editor

text without opening a box.</p>

<p>Invoking ‘Show Completions’, or hitting <kbd class="kbd docutils literal notranslate">Tab</kbd> after a prefix,

outside of a string and without a preceding ‘.’ opens a box with

keywords, builtin names, and available module-level names.</p>

<p>When editing code in an editor (as oppose to Shell), increase the

available module-level names by running your code

and not restarting the Shell thereafter. This is especially useful

after adding imports at the top of a file. This also increases

possible attribute completions.</p>

<p>Completion boxes initially exclude names beginning with ‘_’ or, for

modules, not included in ‘__all__’. The hidden names can be accessed

by typing ‘_’ after ‘.’, either before or after the box is opened.</p>

</section>

<section id="calltips">

<span id="id3"></span><h3>Calltips<a class="headerlink" href="#calltips" title="Link to this heading">¶</a></h3>

<p>A calltip is shown automatically when one types <kbd class="kbd docutils literal notranslate">(</kbd> after the name

of an <em>accessible</em> function. A function name expression may include

dots and subscripts. A calltip remains until it is clicked, the cursor

is moved out of the argument area, or <kbd class="kbd docutils literal notranslate">)</kbd> is typed. Whenever the

cursor is in the argument part of a definition, select Edit and “Show

Call Tip” on the menu or enter its shortcut to display a calltip.</p>

<p>The calltip consists of the function’s signature and docstring up to

the latter’s first blank line or the fifth non-blank line. (Some builtin

functions lack an accessible signature.) A ‘/’ or ‘*’ in the signature

indicates that the preceding or following arguments are passed by

position or name (keyword) only. Details are subject to change.</p>

<p>In Shell, the accessible functions depends on what modules have been

imported into the user process, including those imported by Idle itself,

and which definitions have been run, all since the last restart.</p>

<p>For example, restart the Shell and enter <code class="docutils literal notranslate"><span class="pre">itertools.count(</span></code>. A calltip

appears because Idle imports itertools into the user process for its own

use. (This could change.) Enter <code class="docutils literal notranslate"><span class="pre">turtle.write(</span></code> and nothing appears.

Idle does not itself import turtle. The menu entry and shortcut also do

nothing. 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>

will display a calltip.</p>

<p>In an editor, import statements have no effect until one runs the file.

One might want to run a file after writing import statements, after

adding function definitions, or after opening an existing file.</p>

</section>

<section id="format-block">

<span id="id4"></span><h3>Format block<a class="headerlink" href="#format-block" title="Link to this heading">¶</a></h3>

<p>Reformat Paragraph rewraps a block (‘paragraph’) of contiguous equally

indented non-blank comments, a similar block of text within a multiline

string, or a selected subset of either.

If needed, add a blank line to separate string from code.

Partial lines in a selection expand to complete lines.

The resulting lines have the same indent as before

but have maximum total length of N columns (characters).

Change the default N of 72 on the Window tab of IDLE Settings.</p>

</section>

<section id="code-context">

<span id="id5"></span><h3>Code Context<a class="headerlink" href="#code-context" title="Link to this heading">¶</a></h3>

<p>Within an editor window containing Python code, code context can be toggled

in order to show or hide a pane at the top of the window. When shown, this

pane freezes the opening lines for block code, such as those beginning with

<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

out of view. The size of the pane will be expanded and contracted as needed

to show the all current levels of context, up to the maximum number of

lines defined in the Configure IDLE dialog (which defaults to 15). If there

are no current context lines and the feature is toggled on, a single blank

line will display. Clicking on a line in the context pane will move that

line to the top of the editor.</p>

<p>The text and background colors for the context pane can be configured under

the Highlights tab in the Configure IDLE dialog.</p>

</section>

<section id="shell-window">

<h3>Shell window<a class="headerlink" href="#shell-window" title="Link to this heading">¶</a></h3>

<p>In IDLE’s Shell, enter, edit, and recall complete statements. (Most

consoles and terminals only work with a single physical line at a time).</p>

<p>Submit a single-line statement for execution by hitting <kbd class="kbd docutils literal notranslate">Return</kbd>

with the cursor anywhere on the line. If a line is extended with

Backslash (<kbd class="kbd docutils literal notranslate">\</kbd>), the cursor must be on the last physical line.

Submit a multi-line compound statement by entering a blank line after

the statement.</p>

<p>When one pastes code into Shell, it is not compiled and possibly executed

until one hits <kbd class="kbd docutils literal notranslate">Return</kbd>, as specified above.

One may edit pasted code first.

If one pastes more than one statement into Shell, the result will be a

<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>

<p>Lines containing <code class="docutils literal notranslate"><span class="pre">RESTART</span></code> mean that the user execution process has been

re-started. This occurs when the user execution process has crashed,

when one requests a restart on the Shell menu, or when one runs code

in an editor window.</p>

<p>The editing features described in previous subsections work when entering

code interactively. IDLE’s Shell window also responds to the following:</p>

<ul class="simple">

<li><p><kbd class="kbd docutils literal notranslate">C</kbd>-<kbd class="kbd docutils literal notranslate">c</kbd> attempts to interrupt statement execution (but may fail).</p></li>

<li><p><kbd class="kbd docutils literal notranslate">C</kbd>-<kbd class="kbd docutils literal notranslate">d</kbd> closes Shell if typed at a <code class="docutils literal notranslate"><span class="pre">&gt;&gt;&gt;</span></code> prompt.</p></li>

<li><p><kbd class="kbd docutils literal notranslate">Alt</kbd>-<kbd class="kbd docutils literal notranslate">p</kbd> and <kbd class="kbd docutils literal notranslate">Alt</kbd>-<kbd class="kbd docutils literal notranslate">n</kbd> (<kbd class="kbd docutils literal notranslate">C</kbd>-<kbd class="kbd docutils literal notranslate">p</kbd> and <kbd class="kbd docutils literal notranslate">C</kbd>-<kbd class="kbd docutils literal notranslate">n</kbd> on macOS)

retrieve to the current prompt the previous or next previously

entered statement that matches anything already typed.</p></li>

<li><p><kbd class="kbd docutils literal notranslate">Return</kbd> while the cursor is on any previous statement

appends the latter to anything already typed at the prompt.</p></li>

</ul>

</section>

<section id="text-colors">

<h3>Text colors<a class="headerlink" href="#text-colors" title="Link to this heading">¶</a></h3>

<p>Idle defaults to black on white text, but colors text with special meanings.

For the shell, these are shell output, shell error, user output, and

user error. For Python code, at the shell prompt or in an editor, these are

keywords, builtin class and function names, names following <code class="docutils literal notranslate"><span class="pre">class</span></code> and

<code class="docutils literal notranslate"><span class="pre">def</span></code>, strings, and comments. For any text window, these are the cursor (when

present), found text (when possible), and selected text.</p>

<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>,

<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

pattern-matching statements. However, this highlighting is not perfect and

will 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>

patterns.</p>

<p>Text coloring is done in the background, so uncolorized text is occasionally

visible. To change the color scheme, use the Configure IDLE dialog

Highlighting tab. The marking of debugger breakpoint lines in the editor and

text in popups and dialogs is not user-configurable.</p>

</section>

</section>

<section id="startup-and-code-execution">

<h2>Startup and Code Execution<a class="headerlink" href="#startup-and-code-execution" title="Link to this heading">¶</a></h2>

<p>Upon startup with the <code class="docutils literal notranslate"><span class="pre">-s</span></code> option, IDLE will execute the file referenced by

the 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>.

IDLE 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

referenced is run. If <code class="docutils literal notranslate"><span class="pre">IDLESTARTUP</span></code> is not present, IDLE checks for

<code class="docutils literal notranslate"><span class="pre">PYTHONSTARTUP</span></code>. Files referenced by these environment variables are

convenient places to store functions that are used frequently from the IDLE

shell, or for executing import statements to import common modules.</p>

<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

Tk file is loaded unconditionally. This additional file is <code class="docutils literal notranslate"><span class="pre">.Idle.py</span></code> and is

looked for in the user’s home directory. Statements in this file will be

executed in the Tk namespace, so this file is not useful for importing

functions to be used from IDLE’s Python shell.</p>

<section id="command-line-usage">

<span id="idlelib-cli"></span><h3>Command-line usage<a class="headerlink" href="#command-line-usage" title="Link to this heading">¶</a></h3>

<p>IDLE can be invoked from the command line with various options. The general syntax is:</p>

<div class="highlight-bash notranslate"><div class="highlight"><pre><span></span>python<span class="w"> </span>-m<span class="w"> </span>idlelib<span class="w"> </span><span class="o">[</span>options<span class="o">]</span><span class="w"> </span><span class="o">[</span>file<span class="w"> </span>...<span class="o">]</span>

</pre></div>

</div>

<p>The following options are available:</p>

<dl class="std option">

<dt class="sig sig-object std" id="cmdoption-idle-c">

<span class="sig-name descname"><span class="pre">-c</span></span><span class="sig-prename descclassname"> <span class="pre">&lt;command&gt;</span></span><a class="headerlink" href="#cmdoption-idle-c" title="Link to this definition">¶</a></dt>

<dd><p>Run the specified Python command in the shell window.

For example, pass <code class="docutils literal notranslate"><span class="pre">-c</span> <span class="pre">&quot;print('Hello,</span> <span class="pre">World!')&quot;</span></code>.

On Windows, the outer quotes must be double quotes as shown.</p>

</dd></dl>

<dl class="std option">

<dt class="sig sig-object std" id="cmdoption-idle-d">

<span class="sig-name descname"><span class="pre">-d</span></span><span class="sig-prename descclassname"></span><a class="headerlink" href="#cmdoption-idle-d" title="Link to this definition">¶</a></dt>

<dd><p>Enable the debugger and open the shell window.</p>

</dd></dl>

<dl class="std option">

<dt class="sig sig-object std" id="cmdoption-idle-e">

<span class="sig-name descname"><span class="pre">-e</span></span><span class="sig-prename descclassname"></span><a class="headerlink" href="#cmdoption-idle-e" title="Link to this definition">¶</a></dt>

<dd><p>Open an editor window.</p>

</dd></dl>

<dl class="std option">

<dt class="sig sig-object std" id="cmdoption-idle-h">

<span class="sig-name descname"><span class="pre">-h</span></span><span class="sig-prename descclassname"></span><a class="headerlink" href="#cmdoption-idle-h" title="Link to this definition">¶</a></dt>

<dd><p>Print a help message with legal combinations of options and exit.</p>

</dd></dl>

<dl class="std option">

<dt class="sig sig-object std" id="cmdoption-idle-i">

<span class="sig-name descname"><span class="pre">-i</span></span><span class="sig-prename descclassname"></span><a class="headerlink" href="#cmdoption-idle-i" title="Link to this definition">¶</a></dt>

<dd><p>Open a shell window.</p>

</dd></dl>

<dl class="std option">

<dt class="sig sig-object std" id="cmdoption-idle-r">

<span class="sig-name descname"><span class="pre">-r</span></span><span class="sig-prename descclassname"> <span class="pre">&lt;file&gt;</span></span><a class="headerlink" href="#cmdoption-idle-r" title="Link to this definition">¶</a></dt>

<dd><p>Run the specified file in the shell window.</p>

</dd></dl>

<dl class="std option">

<dt class="sig sig-object std" id="cmdoption-idle-s">

<span class="sig-name descname"><span class="pre">-s</span></span><span class="sig-prename descclassname"></span><a class="headerlink" href="#cmdoption-idle-s" title="Link to this definition">¶</a></dt>

<dd><p>Run the startup file (as defined by the environment variables <span class="target" id="index-7"></span><code class="xref std std-envvar docutils literal notranslate"><span class="pre">IDLESTARTUP</span></code> or <span class="target" id="index-8"></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>) before opening the shell window.</p>

</dd></dl>

<dl class="std option">

<dt class="sig sig-object std" id="cmdoption-idle-t">

<span class="sig-name descname"><span class="pre">-t</span></span><span class="sig-prename descclassname"> <span class="pre">&lt;title&gt;</span></span><a class="headerlink" href="#cmdoption-idle-t" title="Link to this definition">¶</a></dt>

<dd><p>Set the title of the shell window.</p>

</dd></dl>

<dl class="std option">

<dt class="sig sig-object std" id="cmdoption-idle-0">

<span class="sig-name descname"><span class="pre">-</span></span><span class="sig-prename descclassname"></span><a class="headerlink" href="#cmdoption-idle-0" title="Link to this definition">¶</a></dt>

<dd><p>Read and execute standard input in the shell window. This option must be the last one before any arguments.</p>

</dd></dl>

<p>If arguments are provided:</p>

<ul class="simple">

<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 <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>, or <code class="docutils literal notranslate"><span class="pre">'-r'</span></code> respectively.

No editor window is opened, even if that is the default set in the <em>Options</em> dialog.</p></li>

<li><p>Otherwise, arguments are treated as files to be opened for editing, and <code class="docutils literal notranslate"><span class="pre">sys.argv</span></code> reflects the arguments passed to IDLE itself.</p></li>

</ul>

</section>

<section id="startup-failure">

<h3>Startup failure<a class="headerlink" href="#startup-failure" title="Link to this heading">¶</a></h3>

<p>IDLE uses a socket to communicate between the IDLE GUI process and the user

code execution process. A connection must be established whenever the Shell

starts or restarts. (The latter is indicated by a divider line that says

‘RESTART’). If the user process fails to connect to the GUI process, it

usually displays a <code class="docutils literal notranslate"><span class="pre">Tk</span></code> error box with a ‘cannot connect’ message

that directs the user here. It then exits.</p>

<p>One specific connection failure on Unix systems results from

misconfigured masquerading rules somewhere in a system’s network setup.

When IDLE is started from a terminal, one will see a message starting

with <code class="docutils literal notranslate"><span class="pre">**</span> <span class="pre">Invalid</span> <span class="pre">host:</span></code>.

The valid value is <code class="docutils literal notranslate"><span class="pre">127.0.0.1</span> <span class="pre">(idlelib.rpc.LOCALHOST)</span></code>.

One 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

terminal window and <code class="docutils literal notranslate"><span class="pre">tcplisten</span> <span class="pre">&lt;same</span> <span class="pre">args&gt;</span></code> in another.</p>

<p>A common cause of failure is a user-written file with the same name as a

standard library module, such as <em>random.py</em> and <em>tkinter.py</em>. When such a

file is located in the same directory as a file that is about to be run,

IDLE cannot import the stdlib file. The current fix is to rename the

user file.</p>

<p>Though less common than in the past, an antivirus or firewall program may

stop the connection. If the program cannot be taught to allow the

connection, then it must be turned off for IDLE to work. It is safe to

allow this internal connection because no data is visible on external

ports. A similar problem is a network mis-configuration that blocks

connections.</p>

<p>Python installation issues occasionally stop IDLE: multiple versions can

clash, or a single installation might need admin access. If one undo the

clash, or cannot or does not want to run as admin, it might be easiest to

completely remove Python and start over.</p>

<p>A zombie pythonw.exe process could be a problem. On Windows, use Task

Manager to check for one and stop it if there is. Sometimes a restart

initiated by a program crash or Keyboard Interrupt (control-C) may fail

to connect. Dismissing the error box or using Restart Shell on the Shell

menu may fix a temporary problem.</p>

<p>When IDLE first starts, it attempts to read user configuration files in

<code class="docutils literal notranslate"><span class="pre">~/.idlerc/</span></code> (~ is one’s home directory). If there is a problem, an error

message should be displayed. Leaving aside random disk glitches, this can

be prevented by never editing the files by hand. Instead, use the

configuration dialog, under Options. Once there is an error in a user

configuration file, the best solution may be to delete it and start over

with the settings dialog.</p>

<p>If IDLE quits with no message, and it was not started from a console, try

starting 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

this results in an error message.</p>

<p>On Unix-based systems with tcl/tk older than <code class="docutils literal notranslate"><span class="pre">8.6.11</span></code> (see

<code class="docutils literal notranslate"><span class="pre">About</span> <span class="pre">IDLE</span></code>) certain characters of certain fonts can cause

a tk failure with a message to the terminal. This can happen either

if one starts IDLE to edit a file with such a character or later

when entering such a character. If one cannot upgrade tcl/tk,

then re-configure IDLE to use a font that works better.</p>

</section>

<section id="running-user-code">

<h3>Running user code<a class="headerlink" href="#running-user-code" title="Link to this heading">¶</a></h3>

<p>With rare exceptions, the result of executing Python code with IDLE is

intended to be the same as executing the same code by the default method,

directly with Python in a text-mode system console or terminal window.

However, the different interface and operation occasionally affect

visible results. For instance, <code class="docutils literal notranslate"><span class="pre">sys.modules</span></code> starts with more entries,

and <code class="docutils literal notranslate"><span class="pre">threading.active_count()</span></code> returns 2 instead of 1.</p>

<p>By default, IDLE runs user code in a separate OS process rather than in

the user interface process that runs the shell and editor. In the execution

process, 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>

with objects that get input from and send output to the Shell window.

The 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

<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>

<p>Sending print output from one process to a text widget in another is

slower than printing to a system terminal in the same process.

This has the most effect when printing multiple arguments, as the string

for each argument, each separator, the newline are sent separately.

For development, this is usually not a problem, but if one wants to

print faster in IDLE, format and join together everything one wants

displayed together and then print a single string. Both format strings

and <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>

<p>IDLE’s standard stream replacements are not inherited by subprocesses

created in the execution process, whether directly by user code or by

modules such as multiprocessing. If such subprocess use <code class="docutils literal notranslate"><span class="pre">input</span></code> from

sys.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,

IDLE should be started in a command line window. (On Windows,

use <code class="docutils literal notranslate"><span class="pre">python</span></code> or <code class="docutils literal notranslate"><span class="pre">py</span></code> rather than <code class="docutils literal notranslate"><span class="pre">pythonw</span></code> or <code class="docutils literal notranslate"><span class="pre">pyw</span></code>.)

The secondary subprocess

will then be attached to that window for input and output.</p>

<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>,

IDLE’s changes are lost and input from the keyboard and output to the screen

will not work correctly.</p>

<p>When Shell has the focus, it controls the keyboard and screen. This is

normally transparent, but functions that directly access the keyboard

and screen will not work. These include system-specific functions that

determine whether a key has been pressed and if so, which.</p>

<p>The IDLE code running in the execution process adds frames to the call stack

that would not be there otherwise. IDLE wraps <code class="docutils literal notranslate"><span class="pre">sys.getrecursionlimit</span></code> and

<code class="docutils literal notranslate"><span class="pre">sys.setrecursionlimit</span></code> to reduce the effect of the additional stack

frames.</p>

<p>When user code raises SystemExit either directly or by calling sys.exit,

IDLE returns to a Shell prompt instead of exiting.</p>

</section>

<section id="user-output-in-shell">

<h3>User output in Shell<a class="headerlink" href="#user-output-in-shell" title="Link to this heading">¶</a></h3>

<p>When a program outputs text, the result is determined by the

corresponding output device. When IDLE executes user 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> are connected to the display area of IDLE’s Shell. Some of

its features are inherited from the underlying Tk Text widget. Others

are programmed additions. Where it matters, Shell is designed for development

rather than production runs.</p>

<p>For instance, Shell never throws away output. A program that sends unlimited

output to Shell will eventually fill memory, resulting in a memory error.

In contrast, some system text windows only keep the last n lines of output.

A Windows console, for instance, keeps a user-settable 1 to 9999 lines,

with 300 the default.</p>

<p>A Tk Text widget, and hence IDLE’s Shell, displays characters (codepoints) in

the BMP (Basic Multilingual Plane) subset of Unicode. Which characters are

displayed with a proper glyph and which with a replacement box depends on the

operating system and installed fonts. Tab characters cause the following text

to begin after the next tab stop. (They occur every 8 ‘characters’). Newline

characters cause following text to appear on a new line. Other control

characters are ignored or displayed as a space, box, or something else,

depending on the operating system and font. (Moving the text cursor through

such output with arrow keys may exhibit some surprising spacing behavior.)</p>

<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="gp">&gt;&gt;&gt; </span><span class="n">s</span> <span class="o">=</span> <span class="s1">&#39;a</span><span class="se">\t</span><span class="s1">b</span><span class="se">\a</span><span class="s1">&lt;</span><span class="se">\x02</span><span class="s1">&gt;&lt;</span><span class="se">\r</span><span class="s1">&gt;</span><span class="se">\b</span><span class="s1">c</span><span class="se">\n</span><span class="s1">d&#39;</span> <span class="c1"># Enter 22 chars.</span>

<span class="gp">&gt;&gt;&gt; </span><span class="nb">len</span><span class="p">(</span><span class="n">s</span><span class="p">)</span>

<span class="go">14</span>

<span class="gp">&gt;&gt;&gt; </span><span class="n">s</span> <span class="c1"># Display repr(s)</span>

<span class="go">&#39;a\tb\x07&lt;\x02&gt;&lt;\r&gt;\x08c\nd&#39;</span>

<span class="gp">&gt;&gt;&gt; </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">&#39;&#39;</span><span class="p">)</span> <span class="c1"># Display s as is.</span>

<span class="go"># Result varies by OS and font. Try it.</span>

</pre></div>

</div>

<p>The <code class="docutils literal notranslate"><span class="pre">repr</span></code> function is used for interactive echo of expression

values. It returns an altered version of the input string in which

control codes, some BMP codepoints, and all non-BMP codepoints are

replaced with escape codes. As demonstrated above, it allows one to

identify the characters in a string, regardless of how they are displayed.</p>

<p>Normal and error output are generally kept separate (on separate lines)

from code input and each other. They each get different highlight colors.</p>

<p>For SyntaxError tracebacks, the normal ‘^’ marking where the error was

detected is replaced by coloring the text with an error highlight.

When code run from a file causes other exceptions, one may right click

on a traceback line to jump to the corresponding line in an IDLE editor.

The file will be opened if necessary.</p>

<p>Shell has a special facility for squeezing output lines down to a

‘Squeezed text’ label. This is done automatically

for output over N lines (N = 50 by default).

N can be changed in the PyShell section of the General

page of the Settings dialog. Output with fewer lines can be squeezed by

right clicking on the output. This can be useful lines long enough to slow

down scrolling.</p>

<p>Squeezed output is expanded in place by double-clicking the label.

It can also be sent to the clipboard or a separate view window by

right-clicking the label.</p>

</section>

<section id="developing-tkinter-applications">

<h3>Developing tkinter applications<a class="headerlink" href="#developing-tkinter-applications" title="Link to this heading">¶</a></h3>

<p>IDLE is intentionally different from standard Python in order to

facilitate 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>

<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

in IDLE and a tk window appears. In standard Python, one must also enter

<code class="docutils literal notranslate"><span class="pre">root.update()</span></code> to see the window. IDLE does the equivalent in the

background, about 20 times a second, which is about every 50 milliseconds.

Next 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,

nothing visibly changes in standard Python until one enters <code class="docutils literal notranslate"><span class="pre">root.update()</span></code>.</p>

<p>Most tkinter programs run <code class="docutils literal notranslate"><span class="pre">root.mainloop()</span></code>, which usually does not

return until the tk app is destroyed. If the program is run with

<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">&gt;&gt;&gt;</span></code> shell prompt does not

appear until <code class="docutils literal notranslate"><span class="pre">mainloop()</span></code> returns, at which time there is nothing left

to interact with.</p>

<p>When running a tkinter program from an IDLE editor, one can comment out

the mainloop call. One then gets a shell prompt immediately and can

interact with the live application. One just has to remember to

re-enable the mainloop call when running in standard Python.</p>

</section>

<section id="running-without-a-subprocess">

<h3>Running without a subprocess<a class="headerlink" href="#running-without-a-subprocess" title="Link to this heading">¶</a></h3>

<p>By default, IDLE executes user code in a separate subprocess via a socket,

which uses the internal loopback interface. This connection is not

externally visible and no data is sent to or received from the internet.

If firewall software complains anyway, you can ignore it.</p>

<p>If the attempt to make the socket connection fails, Idle will notify you.

Such failures are sometimes transient, but if persistent, the problem

may be either a firewall blocking the connection or misconfiguration of

a particular system. Until the problem is fixed, one can run Idle with

the -n command line switch.</p>

<p>If IDLE is started with the -n command line switch it will run in a

single process and will not create the subprocess which runs the RPC

Python execution server. This can be useful if Python cannot create

the subprocess or the RPC socket interface on your platform. However,

in this mode user code is not isolated from IDLE itself. Also, the

environment is not restarted when Run/Run Module (F5) is selected. If

your code has been modified, you must reload() the affected modules and

re-import any specific items (e.g. from foo import baz) if the changes

are to take effect. For these reasons, it is preferable to run IDLE

with the default subprocess if at all possible.</p>

<div class="deprecated">

<p><span class="versionmodified deprecated">Deprecated since version 3.4.</span></p>

</div>

</section>

</section>

<section id="help-and-preferences">

<h2>Help and Preferences<a class="headerlink" href="#help-and-preferences" title="Link to this heading">¶</a></h2>

<section id="help-sources">

<span id="id6"></span><h3>Help sources<a class="headerlink" href="#help-sources" title="Link to this heading">¶</a></h3>

<p>Help menu entry “IDLE Help” displays a formatted html version of the

IDLE chapter of the Library Reference. The result, in a read-only

tkinter text window, is close to what one sees in a web browser.

Navigate through the text with a mousewheel,

the scrollbar, or up and down arrow keys held down.

Or click the TOC (Table of Contents) button and select a section

header in the opened box.</p>

<p>Help menu entry “Python Docs” opens the extensive sources of help,

including tutorials, available at <code class="docutils literal notranslate"><span class="pre">docs.python.org/x.y</span></code>, where ‘x.y’

is the currently running Python version. If your system

has an off-line copy of the docs (this may be an installation option),

that will be opened instead.</p>

<p>Selected URLs can be added or removed from the help menu at any time using the

General tab of the Configure IDLE dialog.</p>

</section>

<section id="setting-preferences">

<span id="preferences"></span><h3>Setting preferences<a class="headerlink" href="#setting-preferences" title="Link to this heading">¶</a></h3>

<p>The font preferences, highlighting, keys, and general preferences can be

changed via Configure IDLE on the Option menu.

Non-default user settings are saved in a <code class="docutils literal notranslate"><span class="pre">.idlerc</span></code> directory in the user’s

home directory. Problems caused by bad user configuration files are solved

by editing or deleting one or more of the files in <code class="docutils literal notranslate"><span class="pre">.idlerc</span></code>.</p>

<p>On the Font tab, see the text sample for the effect of font face and size

on multiple characters in multiple languages. Edit the sample to add

other characters of personal interest. Use the sample to select

monospaced fonts. If particular characters have problems in Shell or an

editor, add them to the top of the sample and try changing first size

and then font.</p>

<p>On the Highlights and Keys tab, select a built-in or custom color theme

and key set. To use a newer built-in color theme or key set with older

IDLEs, save it as a new custom theme or key set and it well be accessible

to older IDLEs.</p>

</section>

<section id="idle-on-macos">

<h3>IDLE on macOS<a class="headerlink" href="#idle-on-macos" title="Link to this heading">¶</a></h3>

<p>Under System Preferences: Dock, one can set “Prefer tabs when opening

documents” to “Always”. This setting is not compatible with the tk/tkinter

GUI framework used by IDLE, and it breaks a few IDLE features.</p>

</section>

<section id="extensions">

<h3>Extensions<a class="headerlink" href="#extensions" title="Link to this heading">¶</a></h3>

<p>IDLE contains an extension facility. Preferences for extensions can be

changed with the Extensions tab of the preferences dialog. See the

beginning of config-extensions.def in the idlelib directory for further

information. The only current default extension is zzdummy, an example

also used for testing.</p>

</section>

</section>

<section id="module-idlelib">

<span id="idlelib-implementation-of-idle-application"></span><h2>idlelib — implementation of IDLE application<a class="headerlink" href="#module-idlelib" title="Link to this heading">¶</a></h2>

<p><strong>Source code:</strong> <a class="extlink-source reference external" href="https://github.com/python/cpython/tree/main/Lib/idlelib">Lib/idlelib</a></p>

<hr class="docutils" />

<p>The Lib/idlelib package implements the IDLE application. See the rest

of this page for how to use IDLE.</p>

<p>The files in idlelib are described in idlelib/README.txt. Access it

either in idlelib or click Help =&gt; About IDLE on the IDLE menu. This

file also maps IDLE menu items to the code that implements the item.

Except for files listed under ‘Startup’, the idlelib code is ‘private’ in

sense that feature changes can be backported (see <span class="target" id="index-9"></span><a class="pep reference external" href="https://peps.python.org/pep-0434/"><strong>PEP 434</strong></a>).</p>

</section>

</section>