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
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.
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.)
Arrow keys move the cursor one character or line.
C-LeftArrow and C-RightArrow moves left or right one word.
Home and End go to the beginning or end of the line.
Page Up and Page Down go up or down one screen.
C-Home and C-End go to beginning or end of the file.
Backspace and Del (or C-d) delete the previous
or next character.
C-Backspace and C-Del delete one word left or right.
C-k deletes ('kills') everything to the right.
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 [x] Regular expression is checked, the
target is interpreted according to the Python re module.
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 os.sep or
os.altsep immediately after an opening quote. (On Windows,
one can specify a drive first.) Move into subdirectories by typing a
directory name and a separator.
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 itertools.count(. A calltip
appears because Idle imports itertools into the user process for its own
use. (This could change.) Enter turtle.write( and nothing appears.
Idle does not itself import turtle. The menu entry and shortcut also do
nothing. Enter import turtle. Thereafter, turtle.write(
will display a calltip.
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
class, def, or if 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.
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
SyntaxError when multiple statements are compiled as if they were one.
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:
C-c attempts to interrupt statement execution (but may fail).
C-d closes Shell if typed at a >>> prompt.
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.
Return while the cursor is on any previous statement
appends the latter to anything already typed at the prompt.
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 class and
def, strings, and comments. For any text window, these are the cursor (when
present), found text (when possible), and selected text.
IDLE also highlights the soft keywords match,
case, and _ in
pattern-matching statements. However, this highlighting is not perfect and
will be incorrect in some rare cases, including some _-s in case
patterns.
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 -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.
命令列用法
IDLE can be invoked from the command line with various options. The general syntax is:
python -m idlelib [options] [file ...]
The following options are available:
-
-c <command>
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.
-
-d
Enable the debugger and open the shell window.
-
-e
Open an editor window.
-
-h
Print a help message with legal combinations of options and exit.
-
-i
Open a shell window.
-
-r <file>
Run the specified file in the shell window.
-
-s
Run the startup file (as defined by the environment variables IDLESTARTUP or PYTHONSTARTUP) before opening the shell window.
-
-t <title>
Set the title of the shell window.
-
-
Read and execute standard input in the shell window. This option must be the last one before any arguments.
If arguments are provided:
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.
Otherwise, arguments are treated as files to be opened for editing, and sys.argv reflects the arguments passed to IDLE itself.
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 Tk error box with a 'cannot connect' message
that directs the user here. It then exits.
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 ** Invalid host:.
The valid value is 127.0.0.1 (idlelib.rpc.LOCALHOST).
One can diagnose with tcpconnect -irv 127.0.0.1 6543 in one
terminal window and tcplisten <same args> in another.
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
~/.idlerc/ (~ 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.
If IDLE quits with no message, and it was not started from a console, try
starting it from a console or terminal (python -m idlelib) and see if
this results in an error message.
On Unix-based systems with tcl/tk older than 8.6.11 (see
About IDLE) 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.
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, sys.modules starts with more entries,
and threading.active_count() returns 2 instead of 1.
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 sys.stdin, sys.stdout, and sys.stderr
with objects that get input from and send output to the Shell window.
The original values stored in sys.__stdin__, sys.__stdout__, and
sys.__stderr__ are not touched, but may be None.
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 str.join() can help combine fields and lines.
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 input from
sys.stdin or
