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bpo-23220: Explain how IDLE's Shell displays output (GH-10356) 

Add a new subsection to the doc.
(cherry picked from commit 75d9d59ab3)

Co-authored-by: Terry Jan Reedy <tjreedy@udel.edu>
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Miss Islington (bot) 2018-11-06 10:27:20 -08:00 committed by GitHub
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60
Doc/library/idle.rst
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@ -502,8 +502,16 @@ or immediately run an existing file before editing.
Python Shell window
^^^^^^^^^^^^^^^^^^^
The editing features described above work when entering code interactively.
IDLE's Shell window also responds to the following keys.
With IDLE's Shell, one enters, edits, and recalls complete statements.
Most consoles and terminals only work with a single physical line at a time.
When one pastes code into Shell, it is not compiled and possibly executed
until one hits :kbd:`Return`. One may edit pasted code first.
If one pastes more that one statement into Shell, the result will be a
:exc:`SyntaxError` when multiple statements are compiled as if they were one.
The editing features described in previous subsections work when entering
code interactively. IDLE's Shell window also responds to the following keys.
* :kbd:`C-c` interrupts executing command
@ -520,16 +528,6 @@ IDLE's Shell window also responds to the following keys.
* :kbd:`Return` while on any previous command retrieves that command
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 for extra long lines.
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.
Text colors
^^^^^^^^^^^
@ -666,6 +664,44 @@ If ``sys`` is reset by user code, such as with ``importlib.reload(sys)``,
IDLE's changes are lost and input from the keyboard and output to the screen
will not work correctly.
User output in Shell
^^^^^^^^^^^^^^^^^^^^
When a program outputs text, the result is determined by the
corresponding output device. When IDLE executes user code, ``sys.stdout``
and ``sys.stderr`` are connected to the display area of IDLE's Shell. Some of
its features are inherited from the underlying Tk Text widget. Others
are programmed additions.
Text widgets display a subset of Unicode, the Basic Multilingual Plane (BMP).
Which characters get a proper glyph instead of a replacement box depends on
the operating system and installed fonts. Newline characters cause following
text to appear on a new line, but other control characters are replaced
with a box. But note that the ``repr()`` function, which is used for
interactive echo of expression values, replaces control characters
with escape codes before they are output.
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
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

53
Lib/idlelib/help.html
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@ -501,8 +501,14 @@ or immediately run an existing file before editing.</p>
</div>
<div class="section" id="python-shell-window">
<h3>Python Shell window<a class="headerlink" href="#python-shell-window" title="Permalink to this headline"></a></h3>
<p>The editing features described above work when entering code interactively.
IDLE’s Shell window also responds to the following keys.</p>
<p>With IDLE’s Shell, one enters, edits, and recalls complete statements.
Most consoles and terminals only work with a single physical line at a time.</p>
<p>When one pastes code into Shell, it is not compiled and possibly executed
until one hits <kbd class="kbd docutils literal notranslate">Return</kbd>. One may edit pasted code first.
If one pastes more that one statement into Shell, the result will be a
<a class="reference internal" href="exceptions.html#SyntaxError" title="SyntaxError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">SyntaxError</span></code></a> when multiple statements are compiled as if they were one.</p>
<p>The editing features described in previous subsections work when entering
code interactively. IDLE’s Shell window also responds to the following keys.</p>
<ul>
<li><p class="first"><kbd class="kbd docutils literal notranslate">C-c</kbd> interrupts executing command</p>
</li>
@ -518,14 +524,6 @@ OS X use <kbd class="kbd docutils literal notranslate">C-p</kbd>.</li>
</ul>
</li>
</ul>
<p>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 for extra long lines.</p>
<p>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.</p>
</div>
<div class="section" id="text-colors">
<h3>Text colors<a class="headerlink" href="#text-colors" title="Permalink to this headline"></a></h3>
@ -644,6 +642,38 @@ will then be attached to that window for input and output.</p>
IDLE’s changes are lost and input from the keyboard and output to the screen
will not work correctly.</p>
</div>
<div class="section" id="user-output-in-shell">
<h3>User output in Shell<a class="headerlink" href="#user-output-in-shell" title="Permalink to this headline"></a></h3>
<p>When a program outputs text, the result is determined by the
corresponding output device. When IDLE executes user code, <code class="docutils literal notranslate"><span class="pre">sys.stdout</span></code>
and <code class="docutils literal notranslate"><span class="pre">sys.stderr</span></code> are connected to the display area of IDLE’s Shell. Some of
its features are inherited from the underlying Tk Text widget. Others
are programmed additions.</p>
<p>Text widgets display a subset of Unicode, the Basic Multilingual Plane (BMP).
Which characters get a proper glyph instead of a replacement box depends on
the operating system and installed fonts. Newline characters cause following
text to appear on a new line, but other control characters are replaced
with a box. But note that the <code class="docutils literal notranslate"><span class="pre">repr()</span></code> function, which is used for
interactive echo of expression values, replaces control characters
with escape codes before they are output.</p>
<p>Normal and error output are generally kept separate (on separate lines)
from code input and each other. They each get different highlight colors.</p>
<p>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.</p>
<p>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.</p>
<p>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.</p>
</div>
<div class="section" id="developing-tkinter-applications">
<h3>Developing tkinter applications<a class="headerlink" href="#developing-tkinter-applications" title="Permalink to this headline"></a></h3>
<p>IDLE is intentionally different from standard Python in order to
@ -763,6 +793,7 @@ also used for testing.</p>
<li><a class="reference internal" href="#command-line-usage">Command line usage</a></li>
<li><a class="reference internal" href="#startup-failure">Startup failure</a></li>
<li><a class="reference internal" href="#running-user-code">Running user code</a></li>
<li><a class="reference internal" href="#user-output-in-shell">User output in Shell</a></li>
<li><a class="reference internal" href="#developing-tkinter-applications">Developing tkinter applications</a></li>
<li><a class="reference internal" href="#running-without-a-subprocess">Running without a subprocess</a></li>
</ul>
@ -851,7 +882,7 @@ also used for testing.</p>
<br />
<br />
Last updated on Nov 05, 2018.
Last updated on Nov 06, 2018.
<a href="https://docs.python.org/3/bugs.html">Found a bug</a>?
<br />

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Misc/NEWS.d/next/IDLE/2018-11-05-23-23-00.bpo-23220.H3SAWE.rst Normal file
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Explain how IDLE's Shell displays output.