Terry J. Reedy added the comment:
Your report touches on four different issues.
1. IDLE uses tkinter for the GUI and tkinter wraps tcl/tk 8.6 or earlier, which
only handles Basic Multilingual Plane chars (codepoints 0000 to FFFF). The gun
and knife chars are out of that range. I have read that 8.7 will handle all
unicode chars and that it might be released this year. This will fix multiple
IDLE issues (#21084, #22742, #13153, #14304).
2. Until 3.3, CPython used two internal unicode encoding schemes: Narrow and
wide builds. Narrow builds used pairs of surrogate chars in the BMP to
represent chars not in the BMP. So your '3 char' string is stored as 5 chars.
# -*- coding: utf-8 -*-
text = u"🔫 🔪"
for c in text:
print(ord(c))
*prints, on 2.7.13 on Windows
55357
56619
32
55357
56618
Windows releases and a few *nix releases used narrow builds. I have Windows,
so I could copy and paste your string and run the above. Most *nix releases
used wide builds and could not.
In 3.3, CPython switched to a flexible representation used on all releases.
Like earlier wide builds, it does not use surrogate chars, and the above no
longer loads into a text widget, let alone run.
3. Any exception not caught by IDLE generates a traceback that appears on the
console used to start IDLE, if there is one. Otherwise, it is lost. Running
"<python3> -m idlelib" in a console and loading the code above results in a
traceback ending with "_tkinter.TclError: character U+1f52b is above the range
(U+000)-(U+ffff) allowed by Tcl".
I have though about (and previously commented about) trying to put such
messages in a tk message box when IDLE and tk are still functioning well enough
to do so before stopping.
4. It appears the IDLE opens a file that is not already open by creating a
blank editor window and then loading the file into it. In this case, when the
load fails, a frozen window is left that blocks IDLE closing. This nasty
behavior, which I verified, is new to me, so I am leaving this issue open
specifically for this bug.
A likely fix is to catch TclError in the appropriate place (not yet known to
me), recover (delete the new EditorWindow and ???), display an explanatory
error message, and continue when user hits [OK].
We already have a test string. If needed, I will try to separate 'opening a
file name' from 'reading the contents', so a test can use a simple mock file
object.
If a file were opened and read *before* creating a new window, there would be
less cleanup to do.
----------
stage: -> needs patch
title: IDLE got unexpexted bahavior when trying to use some characters -> IDLE
freezes when opening a file with astral characters
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Python tracker <rep...@bugs.python.org>
<http://bugs.python.org/issue30019>
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