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# 25.5. IDLE

IDLE is the Python IDE built with the `tkinter` GUI toolkit.

IDLE has the following features:

- coded in 100% pure Python, using the `tkinter` GUI toolkit
- cross-platform: works on Windows and Unix
- multi-window text editor with multiple undo, Python colorizing and many other features, e.g. smart indent and call tips
- Python shell window (a.k.a. interactive interpreter)
- debugger (not complete, but you can set breakpoints, view and step)

## 25.5.1. Menus

### 25.5.1.1. File menu

New window
  create a new editing window
Open...
  open an existing file
Open module...
  open an existing module (searches sys.path)
Class browser
  show classes and methods in current file
Path browser
  show sys.path directories, modules, classes and methods

Save
  save current window to the associated file (unsaved windows have a * before and after the window title)
Save As...
  save current window to new file, which becomes the associated file
Save Copy As...
  save current window to different file without changing the associated file
Close
  close current window (asks to save if unsaved)
Exit
  close all windows and quit IDLE (asks to save if unsaved)

### 25.5.1.2. Edit menu

Undo
  Undo last change to current window (max 1000 changes)
Redo
  Redo last undone change to current window
Cut
  Copy selection into system-wide clipboard; then delete selection
Copy
  Copy selection into system-wide clipboard
Paste
  Insert system-wide clipboard into window
Select All
  Select the entire contents of the edit buffer
Find...
  Open a search dialog box with many options
Find again
  Repeat last search
Find selection
  Search for the string in the selection
Find in Files...
  Open a search dialog box for searching files
Replace...
  Open a search-and-replace dialog box
Go to line
  Ask for a line number and show that line
Indent region
  Shift selected lines right 4 spaces
Dedent region
  Shift selected lines left 4 spaces
Comment out region
  Insert ## in front of selected lines
Uncomment region
  Remove leading # or ## from selected lines
Tabify region
  Turns leading stretches of spaces into tabs
Untabify region
  Turn all tabs into the right number of spaces
Expand word
  Expand the word you have typed to match another word in the same buffer; repeat to get a different expansion
Format Paragraph
  Reformat the current blank-line-separated paragraph
Import module
  Import or reload the current module
Run script
  Execute the current file in the __main__ namespace

### 25.5.1.3. Windows menu

Zoom Height
  toggles the window between normal size (24x80) and maximum height.

The rest of this menu lists the names of all open windows; select one to bring it to the foreground (deiconifying it if necessary).

### 25.5.1.4. Debug menu (in the Python Shell window only)

Go to file/line
  look around the insert point for a filename and linenumber, open the file, and show the line.
Open stack viewer
  show the stack traceback of the last exception
Debugger toggle
  Run commands in the shell under the debugger
JIT Stack viewer toggle
  Open stack viewer on traceback

## 25.5.2. Basic editing and navigation

- `Backspace` deletes to the left; `Del` deletes to the right
- Arrow keys and `Page Up`/`Page Down` to move around
- `Home`/`End` go to begin/end of line
- `C-Home`/`C-End` go to begin/end of file
- Some Emacs bindings may also work, including `C-B`, `C-P`, `C-A`, `C-E`, `C-D`, `C-L`

### 25.5.2.1. 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 1-4 spaces (in the Python Shell window one tab). See also the indent/dedent region commands in the edit menu.

### 25.5.2.2. Python Shell window

- `C-C` interrupts executing command
- `C-D` sends end-of-file; closes window if typed at a `>>>` prompt
- `Alt-p` retrieves previous command matching what you have typed
- `Alt-n` retrieves next
- `Return` while on any previous command retrieves that command
- `Alt-/` (Expand word) is also useful here

## 25.5.3. Syntax colors

The coloring is applied in a background “thread,” so you may occasionally see uncolorized text. To change the color scheme, edit the `[Colors]` section in `config.txt`.

Python syntax colors:
  Keywords
    orange
  Strings
    green
  Comments
    red
  Definitions
    blue
Shell colors:
  Console output
    brown
  stdout
    blue
  stderr
    dark green
  stdin
    black

## 25.5.4. Startup

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 referenced is run. If `IDLESTARTUP` is not present, Idle checks for `PYTHONSTARTUP`. 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.

In addition, `Tk` also loads a startup file if it is present. Note that the Tk file is loaded unconditionally. This additional file is `.Idle.py` 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.

### 25.5.4.1. Command line usage

    idle.py [-c command] [-d] [-e] [-s] [-t title] [arg] ...

    -c command  run this command
    -d          enable debugger
    -e          edit mode; arguments are files to be edited
    -s          run $IDLESTARTUP or $PYTHONSTARTUP first
    -t title    set title of shell window

If there are arguments:

1. If -e is used, arguments are files opened for editing and `sys.argv` reflects the arguments passed to IDLE itself.
2. Otherwise, if -c is used, all arguments are placed in `sys.argv[1:...]`, with `sys.argv[0]` set to `'-c'`.
3. Otherwise, if neither -e nor -c is used, the first argument is a script which is executed with the remaining arguments in `sys.argv[1:...]` and `sys.argv[0]` set to the script name. If the script name is ‘-‘, no script is executed but an interactive Python session is started; the arguments are still available in `sys.argv`.

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