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IDLE¶

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Source code: Lib/idlelib/

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IDLE — Python editor and shell¶

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Source code: Lib/idlelib/

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IDLE is Python’s Integrated Development and Learning Environment.

IDLE has the following features:

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  • coded in 100% pure Python, using the tkinter GUI toolkit

  • cross-platform: works mostly the same on Windows, Unix, and macOS

  • Python shell window (interactive interpreter) with colorizing of code input, output, and error messages

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    Navigation

    of global and local namespaces

  • configuration, browsers, and other dialogs

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Run menu (Editor window only)¶

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Run menu (Editor window only)¶

Run Module

Do Check Module. If no error, restart the shell to clean the environment, then execute the module. Output is displayed in the Shell @@ -280,9 +186,9 @@

Edit menu (Shell and Editor) -

Shell menu (Shell window only)¶

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Shell menu (Shell window only)¶

View Last Restart

Scroll the shell window to the last Shell restart.

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Shell menu (Shell window only) -

Debug menu (Shell window only)¶

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Debug menu (Shell window only)¶

Go to File/Line

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 @@ -317,9 +223,9 @@

Debug menu (Shell window only) -

Options menu (Shell and Editor)¶

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Options menu (Shell and Editor)¶

Configure IDLE

Open a configuration dialog and change preferences for the following: fonts, indentation, keybindings, text color themes, startup windows and @@ -349,14 +255,14 @@

Options menu (Shell and Editor) -

Window menu (Shell and Editor)¶

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Window menu (Shell and Editor)¶

Lists the names of all open windows; select one to bring it to the foreground (deiconifying it if necessary).

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Help menu (Shell and Editor)¶

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Help menu (Shell and Editor)¶

About IDLE

Display version, copyright, license, credits, and more.

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Help menu (Shell and Editor)Help sources subsection below for more on Help menu choices.

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Context Menus¶

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Context menus¶

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.

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Help menu (Shell and Editor) -

Editing and navigation¶

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Editor windows¶

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Editing and Navigation¶

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Editor windows¶

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.

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Editor windows -

Key bindings¶

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In this section, ‘C’ refers to the Control key on Windows and Unix and -the Command key on macOS.

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  • Backspace deletes to the left; Del deletes to the right

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  • C-Backspace delete word left; C-Del delete word to the right

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  • Arrow keys and Page Up/Page Down to move around

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  • C-LeftArrow and C-RightArrow moves by words

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  • Home/End go to begin/end of line

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  • C-Home/C-End go to begin/end of file

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  • Some useful Emacs bindings are inherited from Tcl/Tk:

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    • C-a beginning of line

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    • C-e end of line

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    • C-k kill line (but doesn’t put it in clipboard)

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    • C-l center window around the insertion point

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    • C-b go backward one character without deleting (usually you can -also use the cursor key for this)

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    • C-f go forward one character without deleting (usually you can -also use the cursor key for this)

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    • C-p go up one line (usually you can also use the cursor key for -this)

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    • C-d delete next character

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Key bindings¶

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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.

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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 Control key on Windows and +Unix and the Command key on macOS. (And all such discussions +assume that the keys have not been re-bound to something else.)

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  • Arrow keys move the cursor one character or line.

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  • C-LeftArrow and C-RightArrow moves left or right one word.

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  • Home and End go to the beginning or end of the line.

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  • Page Up and Page Down go up or down one screen.

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  • C-Home and C-End go to beginning or end of the file.

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  • Backspace and Del (or C-d) delete the previous +or next character.

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  • C-Backspace and C-Del delete one word left or right.

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  • C-k deletes (‘kills’) everything to the right.

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Standard keybindings (like C-c to copy and C-v to paste) +

Standard keybindings (like C-c to copy and C-v to paste) may work. Keybindings are selected in the Configure IDLE dialog.

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Automatic indentation¶

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Automatic indentation¶

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, Backspace deletes up @@ -465,9 +365,16 @@

Automatic indentation

See also the indent/dedent region commands on the Format menu.

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Completions¶

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Search and Replace¶

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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 [x] Regular expression is checked, the +target is interpreted according to the Python re module.

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Completions¶

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 @@ -489,7 +396,7 @@

Automatic indentation

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 C-space. If one types a prefix for the desired name +key is C-space. 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 @@ -509,9 +416,9 @@

Automatic indentationCompletion 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.

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Calltips¶

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Calltips¶

A calltip is shown automatically when one types ( after the name of an accessible function. A function name expression may include dots and subscripts. A calltip remains until it is clicked, the cursor @@ -535,9 +442,20 @@

Automatic indentationIn 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.

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Code Context¶

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Format block¶

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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.

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Code Context¶

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 @@ -550,33 +468,39 @@

Automatic indentation

The text and background colors for the context pane can be configured under the Highlights tab in the Configure IDLE dialog.

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Python Shell window¶

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With IDLE’s Shell, one enters, edits, and recalls complete statements. -Most consoles and terminals only work with a single physical line at a time.

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Shell window¶

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In IDLE’s Shell, enter, edit, and recall complete statements. (Most +consoles and terminals only work with a single physical line at a time).

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Submit a single-line statement for execution by hitting Return +with the cursor anywhere on the line. If a line is extended with +Backslash (\), the cursor must be on the last physical line. +Submit a multi-line compound statement by entering a blank line after +the statement.

When one pastes code into Shell, it is not compiled and possibly executed -until one hits Return. One may edit pasted code first. -If one pastes more that one statement into Shell, the result will be a +until one hits Return, as specified above. +One may edit pasted code first. +If one pastes more than one statement into Shell, the result will be a SyntaxError when multiple statements are compiled as if they were one.

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Lines containing RESTART 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.

The editing features described in previous subsections work when entering -code interactively. IDLE’s Shell window also responds to the following keys.

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  • C-c interrupts executing command

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  • C-d sends end-of-file; closes window if typed at a >>> prompt

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  • Alt-/ (Expand word) is also useful to reduce typing

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    Command history

    +code interactively. IDLE’s Shell window also responds to the following:

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    • Alt-p retrieves previous command matching what you have typed. On -macOS use C-p.

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    • Alt-n retrieves next. On macOS use C-n.

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    • Return while on any previous command retrieves that command

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    • C-c attempts to interrupt statement execution (but may fail).

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    • C-d closes Shell if typed at a >>> prompt.

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    • Alt-p and Alt-n (C-p and C-n on macOS) +retrieve to the current prompt the previous or next previously +entered statement that matches anything already typed.

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    • Return while the cursor is on any previous statement +appends the latter to anything already typed at the prompt.

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Text colors¶

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Text colors¶

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 @@ -592,10 +516,10 @@

Text colors -

Startup and code execution¶

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Startup and Code Execution¶

Upon startup with the -s option, IDLE will execute the file referenced by the environment variables IDLESTARTUP or PYTHONSTARTUP. IDLE first checks for IDLESTARTUP; if IDLESTARTUP is present the file @@ -608,33 +532,79 @@

Startup and code execution -

Command line usage¶

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idle.py [-c command] [-d] [-e] [-h] [-i] [-r file] [-s] [-t title] [-] [arg] ...
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--c command  run command in the shell window
--d          enable debugger and open shell window
--e          open editor window
--h          print help message with legal combinations and exit
--i          open shell window
--r file     run file in shell window
--s          run $IDLESTARTUP or $PYTHONSTARTUP first, in shell window
--t title    set title of shell window
--           run stdin in shell (- must be last option before args)
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Command-line usage¶

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

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python -m idlelib [options] [file ...]
 
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If there are arguments:

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The following options are available:

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+-c <command>¶
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Run the specified Python command in the shell window. +For example, pass -c "print('Hello, World!')". +On Windows, the outer quotes must be double quotes as shown.

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+-d¶
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Enable the debugger and open the shell window.

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+-e¶
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Open an editor window.

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+-h¶
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Print a help message with legal combinations of options and exit.

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+-i¶
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Open a shell window.

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+-r <file>¶
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Run the specified file in the shell window.

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+-s¶
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Run the startup file (as defined by the environment variables IDLESTARTUP or PYTHONSTARTUP) before opening the shell window.

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+-t <title>¶
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Set the title of the shell window.

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Read and execute standard input in the shell window. This option must be the last one before any arguments.

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If arguments are provided:

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  • If -, -c, or r is used, all arguments are placed in -sys.argv[1:...] and sys.argv[0] is set to '', '-c', -or '-r'. No editor window is opened, even if that is the default -set in the Options dialog.

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  • Otherwise, arguments are files opened for editing and -sys.argv reflects the arguments passed to IDLE itself.

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  • If -, -c, or -r is used, all arguments are placed in sys.argv[1:], +and sys.argv[0] is set to '', '-c', or '-r' respectively. +No editor window is opened, even if that is the default set in the Options dialog.

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  • Otherwise, arguments are treated as files to be opened for editing, and sys.argv reflects the arguments passed to IDLE itself.

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Startup failure¶

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Startup failure¶

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 @@ -684,9 +654,9 @@

Startup failure -

Running user code¶

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Running user code¶

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. @@ -711,7 +681,9 @@

Running user codeinput from sys.stdin or print or write to sys.stdout or sys.stderr, -IDLE should be started in a command line window. The secondary subprocess +IDLE should be started in a command line window. (On Windows, +use python or py rather than pythonw or pyw.) +The secondary subprocess will then be attached to that window for input and output.

If sys is reset by user code, such as with importlib.reload(sys), IDLE’s changes are lost and input from the keyboard and output to the screen @@ -726,9 +698,9 @@

Running user code -

User output in Shell¶

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User output in Shell¶

When a program outputs text, the result is determined by the corresponding output device. When IDLE executes user code, sys.stdout and sys.stderr are connected to the display area of IDLE’s Shell. Some of @@ -780,9 +752,9 @@

User output in ShellSqueezed 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.

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Developing tkinter applications¶

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Developing tkinter applications¶

IDLE is intentionally different from standard Python in order to facilitate development of tkinter programs. Enter import tkinter as tk; root = tk.Tk() in standard Python and nothing appears. Enter the same @@ -800,9 +772,9 @@

Developing tkinter applications -

Running without a subprocess¶

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Running without a subprocess¶

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. @@ -825,12 +797,12 @@

Running without a subprocess

Deprecated since version 3.4.

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