diff options
Diffstat (limited to 'Doc/library')
| -rw-r--r-- | Doc/library/idle.rst | 35 |
1 files changed, 29 insertions, 6 deletions
diff --git a/Doc/library/idle.rst b/Doc/library/idle.rst index 38ab4f1..0faeb6d 100644 --- a/Doc/library/idle.rst +++ b/Doc/library/idle.rst @@ -599,15 +599,15 @@ starting from a console (``python -m idlelib)`` and see if a message appears. IDLE-console differences ^^^^^^^^^^^^^^^^^^^^^^^^ -As much as possible, the result of executing Python code with IDLE is the -same as executing the same code in a console window. However, the different -interface and operation occasionally affect visible results. For instance, -``sys.modules`` starts with more entries. +With rare exceptions, the result of executing Python code with IDLE is +intended to be the same as executing the same code in a console window. +However, the different interface and operation occasionally affect +visible results. For instance, ``sys.modules`` starts with more entries. IDLE also replaces ``sys.stdin``, ``sys.stdout``, and ``sys.stderr`` with objects that get input from and send output to the Shell window. -When this window has the focus, it controls the keyboard and screen. -This is normally transparent, but functions that directly access the keyboard +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. If ``sys`` is reset with ``importlib.reload(sys)``, IDLE's changes are lost and things like ``input``, ``raw_input``, and ``print`` will not work correctly. @@ -617,6 +617,29 @@ Some consoles only work with a single physical line at a time. IDLE uses ``exec`` to run each statement. As a result, ``'__builtins__'`` is always defined for each statement. +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 +in IDLE and a tk window appears. In standard Python, one must also enter +``root.update()`` to see the window. IDLE does the equivalent in the +background, about 20 times a second, which is about every 50 milleseconds. +Next enter ``b = tk.Button(root, text='button'); b.pack()``. Again, +nothing visibly changes in standard Python until one enters ``root.update()``. + +Most tkinter programs run ``root.mainloop()``, which usually does not +return until the tk app is destroyed. If the program is run with +``python -i`` or from an IDLE editor, a ``>>>`` shell prompt does not +appear until ``mainloop()`` returns, at which time there is nothing left +to interact with. + +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 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ |