Source code: Lib/idlelib/ Show
IDLE is Python’s Integrated Development and Learning Environment. IDLE has the following features:
Editing and Navigation¶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. 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. 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. Key bindings¶In this section, ‘C’ refers to the Control key on Windows and Unix and the Command key on macOS.
Standard keybindings (like C-c to copy and C-v to paste) may work. Keybindings are selected in the Configure IDLE dialog. 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 to 4 spaces if they are there. Tab 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. See also the indent/dedent region commands on the Format menu. Search and Replace¶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 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 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 Up, Down, PageUp, PageDown, Home, and End keys; and by a single click within the box. Close the box with Escape, Enter, and double Tab keys or clicks outside the box. A double click within the box selects and closes. 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 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 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. Hitting Tab 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. Invoking ‘Show Completions’, or hitting Tab after a prefix, outside of a string and without a preceding ‘.’ opens a box with keywords, builtin names, and available module-level names. 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. 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. 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 is moved out of the argument area, or ) 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. 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. 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. For example, restart the Shell and enter 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. 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 The text and background colors for the context pane can be configured under the Highlights tab in the Configure IDLE dialog. Shell window¶In IDLE’s Shell, enter, edit, and recall complete statements. (Most consoles and terminals only work with a single physical line at a time). 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, as specified above. One may edit pasted code first. If one pastes more than one statement into Shell, the result will be a Lines containing The editing features described in previous subsections work when entering code interactively. IDLE’s Shell window also responds to the following keys.
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 keywords, builtin class and function names, names following IDLE also highlights the soft keywords 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. Startup and Code Execution¶Upon startup with the In addition, Command line usage¶idle.py [-c command] [-d] [-e] [-h] [-i] [-r file] [-s] [-t title] [-] [arg] ... -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) If there are arguments:
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 ‘RESTART’). If the user
process fails to connect to the GUI process, it usually displays a 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 A common cause of failure is a user-written file with the same name as a standard library module, such as random.py and tkinter.py. 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. 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. 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. 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. When IDLE first starts, it attempts to read user configuration files in If IDLE quits with no message, and it was not started from a console, try starting it from a console or terminal ( On Unix-based systems with tcl/tk older than 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. However, the different interface and operation occasionally affect visible results. For instance, 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 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 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 If 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. The IDLE code running in the execution process adds frames to the call stack that would not be there otherwise. IDLE wraps When user code raises SystemExit either directly or by calling sys.exit, IDLE returns to a Shell prompt instead of exiting. User output in Shell¶When a program outputs text, the result is determined by the corresponding output device. When IDLE executes user code,
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. 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.) >>> s = 'a\tb\a<\x02><\r>\bc\nd' # Enter 22 chars. >>> len(s) 14 >>> s # Display repr(s) 'a\tb\x07<\x02><\r>\x08c\nd' >>> print(s, end='') # Display s as is. # Result varies by OS and font. Try it. The Normal and error output are generally kept separate (on separate lines) from code input and each other. They each get different highlight colors. 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. 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. 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. Developing tkinter applications¶IDLE is intentionally different from standard Python in
order to facilitate development of tkinter programs. Enter Most tkinter programs run 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. 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. If firewall software complains anyway, you can ignore it. 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. 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. Deprecated since version 3.4. Help and Preferences¶Help sources¶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. Help menu entry “Python Docs” opens the extensive sources of help, including tutorials, available at Selected URLs can be added or removed from the help menu at any time using the General tab of the Configure IDLE dialog. Setting preferences¶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 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. 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. IDLE on macOS¶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. Extensions¶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. idlelib¶Source code: Lib/idlelib The Lib/idlelib package implements the IDLE application. See the rest of this page for how to use IDLE. The files in idlelib are described in idlelib/README.txt. Access it either in idlelib or click Help => 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 PEP 434). Is IDLE and shell the same?The shell is the default mode of operation for Python IDLE. When you click on the icon to open the program, the shell is the first thing that you can see. Here, you can see a blank Python interpreter window.
What is a Python shell?The Python Shell is the interpreter that executes your Python programs, other pieces of Python code, or simple commands.
What is IDLE in Python?IDLE is Python's Integrated Development and Learning Environment. IDLE has the following features: coded in 100% pure Python, using the tkinter GUI toolkit. cross-platform: works mostly the same on Windows, Unix, and macOS.
Where is IDLE shell in Python?IDLE is the Python environment we will be using. Look for "IDLE (Python 3.5 32-bit)" entry in the Programs list, under Python 3.5. The IDLE shell window opens up. You can again type in print("hello!") and so forth, and the shell will do the printing.
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