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<h1 class="page-title">PEP 3110 – Catching Exceptions in Python 3000</h1>
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<dl class="rfc2822 field-list simple">
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<dt class="field-odd">Author<span class="colon">:</span></dt>
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<dd class="field-odd">Collin Winter <collinwinter at google.com></dd>
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<dt class="field-even">Status<span class="colon">:</span></dt>
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<dd class="field-even"><abbr title="Accepted and implementation complete, or no longer active">Final</abbr></dd>
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||
<dt class="field-odd">Type<span class="colon">:</span></dt>
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||
<dd class="field-odd"><abbr title="Normative PEP with a new feature for Python, implementation change for CPython or interoperability standard for the ecosystem">Standards Track</abbr></dd>
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<dt class="field-even">Created<span class="colon">:</span></dt>
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||
<dd class="field-even">16-Jan-2006</dd>
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<dt class="field-odd">Python-Version<span class="colon">:</span></dt>
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||
<dd class="field-odd">3.0</dd>
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<dt class="field-even">Post-History<span class="colon">:</span></dt>
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<dd class="field-even"><p></p></dd>
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</dl>
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<hr class="docutils" />
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<section id="contents">
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<details><summary>Table of Contents</summary><ul class="simple">
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<li><a class="reference internal" href="#abstract">Abstract</a></li>
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<li><a class="reference internal" href="#rationale">Rationale</a></li>
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<li><a class="reference internal" href="#grammar-changes">Grammar Changes</a></li>
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||
<li><a class="reference internal" href="#semantic-changes">Semantic Changes</a></li>
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||
<li><a class="reference internal" href="#compatibility-issues">Compatibility Issues</a><ul>
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<li><a class="reference internal" href="#compatibility">2.6 - 3.0 Compatibility</a></li>
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</ul>
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</li>
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<li><a class="reference internal" href="#open-issues">Open Issues</a><ul>
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<li><a class="reference internal" href="#replacing-or-dropping-sys-exc-info">Replacing or Dropping “sys.exc_info()”</a></li>
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||
</ul>
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</li>
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<li><a class="reference internal" href="#implementation">Implementation</a></li>
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<li><a class="reference internal" href="#references">References</a></li>
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||
<li><a class="reference internal" href="#copyright">Copyright</a></li>
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||
</ul>
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||
</details></section>
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||
<section id="abstract">
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<h2><a class="toc-backref" href="#abstract" role="doc-backlink">Abstract</a></h2>
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||
<p>This PEP introduces changes intended to help eliminate ambiguities
|
||
in Python’s grammar, simplify exception classes, simplify garbage
|
||
collection for exceptions and reduce the size of the language in
|
||
Python 3.0.</p>
|
||
</section>
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||
<section id="rationale">
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||
<h2><a class="toc-backref" href="#rationale" role="doc-backlink">Rationale</a></h2>
|
||
<ol class="arabic">
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||
<li><code class="docutils literal notranslate"><span class="pre">except</span></code> clauses in Python 2.x present a syntactic ambiguity
|
||
where the parser cannot differentiate whether<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="k">except</span> <span class="o"><</span><span class="n">expression</span><span class="o">></span><span class="p">,</span> <span class="o"><</span><span class="n">expression</span><span class="o">></span><span class="p">:</span>
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||
</pre></div>
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</div>
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<p>should be interpreted as</p>
|
||
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="k">except</span> <span class="o"><</span><span class="nb">type</span><span class="o">></span><span class="p">,</span> <span class="o"><</span><span class="nb">type</span><span class="o">></span><span class="p">:</span>
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||
</pre></div>
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||
</div>
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||
<p>or</p>
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||
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="k">except</span> <span class="o"><</span><span class="nb">type</span><span class="o">></span><span class="p">,</span> <span class="o"><</span><span class="n">name</span><span class="o">></span><span class="p">:</span>
|
||
</pre></div>
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||
</div>
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||
<p>Python 2 opts for the latter semantic, at the cost of requiring the
|
||
former to be parenthesized, like so</p>
|
||
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="k">except</span> <span class="p">(</span><span class="o"><</span><span class="nb">type</span><span class="o">></span><span class="p">,</span> <span class="o"><</span><span class="nb">type</span><span class="o">></span><span class="p">):</span>
|
||
</pre></div>
|
||
</div>
|
||
</li>
|
||
<li>As specified in <a class="pep reference internal" href="../pep-0352/" title="PEP 352 – Required Superclass for Exceptions">PEP 352</a>, the ability to treat exceptions
|
||
as tuples will be removed, meaning this code will no longer work<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="k">except</span> <span class="n">os</span><span class="o">.</span><span class="n">error</span><span class="p">,</span> <span class="p">(</span><span class="n">errno</span><span class="p">,</span> <span class="n">errstr</span><span class="p">):</span>
|
||
</pre></div>
|
||
</div>
|
||
<p>Because the automatic unpacking will no longer be possible, it is
|
||
desirable to remove the ability to use tuples as <code class="docutils literal notranslate"><span class="pre">except</span></code> targets.</p>
|
||
</li>
|
||
<li>As specified in <a class="pep reference internal" href="../pep-0344/" title="PEP 344 – Exception Chaining and Embedded Tracebacks">PEP 344</a>, exception instances in Python 3
|
||
will possess a <code class="docutils literal notranslate"><span class="pre">__traceback__</span></code> attribute. The Open Issues section
|
||
of that PEP includes a paragraph on garbage collection difficulties
|
||
caused by this attribute, namely a “exception -> traceback ->
|
||
stack frame -> exception” reference cycle, whereby all locals are
|
||
kept in scope until the next GC run. This PEP intends to resolve
|
||
this issue by adding a cleanup semantic to <code class="docutils literal notranslate"><span class="pre">except</span></code> clauses in
|
||
Python 3 whereby the target name is deleted at the end of the
|
||
<code class="docutils literal notranslate"><span class="pre">except</span></code> suite.</li>
|
||
<li>In the spirit of <a class="pep reference internal" href="../pep-0020/" title="PEP 20 – The Zen of Python">“there should be one – and preferably only one
|
||
– obvious way to do it”</a>, it is desirable to consolidate
|
||
duplicate functionality. To this end, the <code class="docutils literal notranslate"><span class="pre">exc_value</span></code>,
|
||
<code class="docutils literal notranslate"><span class="pre">exc_type</span></code> and <code class="docutils literal notranslate"><span class="pre">exc_traceback</span></code> attributes of the <code class="docutils literal notranslate"><span class="pre">sys</span></code>
|
||
module <a class="footnote-reference brackets" href="#sys-module" id="id1">[1]</a> will be removed in favor of
|
||
<code class="docutils literal notranslate"><span class="pre">sys.exc_info()</span></code>, which provides the same information. These
|
||
attributes are already listed in <a class="pep reference internal" href="../pep-3100/" title="PEP 3100 – Miscellaneous Python 3.0 Plans">PEP 3100</a> as targeted
|
||
for removal.</li>
|
||
</ol>
|
||
</section>
|
||
<section id="grammar-changes">
|
||
<h2><a class="toc-backref" href="#grammar-changes" role="doc-backlink">Grammar Changes</a></h2>
|
||
<p>In Python 3, the grammar for <code class="docutils literal notranslate"><span class="pre">except</span></code> statements will change
|
||
from <a class="footnote-reference brackets" href="#grammar" id="id2">[4]</a></p>
|
||
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">except_clause</span><span class="p">:</span> <span class="s1">'except'</span> <span class="p">[</span><span class="n">test</span> <span class="p">[</span><span class="s1">','</span> <span class="n">test</span><span class="p">]]</span>
|
||
</pre></div>
|
||
</div>
|
||
<p>to</p>
|
||
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">except_clause</span><span class="p">:</span> <span class="s1">'except'</span> <span class="p">[</span><span class="n">test</span> <span class="p">[</span><span class="s1">'as'</span> <span class="n">NAME</span><span class="p">]]</span>
|
||
</pre></div>
|
||
</div>
|
||
<p>The use of <code class="docutils literal notranslate"><span class="pre">as</span></code> in place of the comma token means that</p>
|
||
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="k">except</span> <span class="p">(</span><span class="ne">AttributeError</span><span class="p">,</span> <span class="n">os</span><span class="o">.</span><span class="n">error</span><span class="p">):</span>
|
||
</pre></div>
|
||
</div>
|
||
<p>can be clearly understood as a tuple of exception classes. This new
|
||
syntax was first proposed by Greg Ewing <a class="footnote-reference brackets" href="#firstproposal" id="id3">[2]</a> and
|
||
endorsed (<a class="footnote-reference brackets" href="#firstproposal" id="id4">[2]</a>, <a class="footnote-reference brackets" href="#renaming" id="id5">[3]</a>) by the BDFL.</p>
|
||
<p>Further, the restriction of the token following <code class="docutils literal notranslate"><span class="pre">as</span></code> from <code class="docutils literal notranslate"><span class="pre">test</span></code>
|
||
to <code class="docutils literal notranslate"><span class="pre">NAME</span></code> means that only valid identifiers can be used as
|
||
<code class="docutils literal notranslate"><span class="pre">except</span></code> targets.</p>
|
||
<p>Note that the grammar above always requires parenthesized tuples as
|
||
exception classes. That way, the ambiguous</p>
|
||
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="k">except</span> <span class="n">A</span><span class="p">,</span> <span class="n">B</span><span class="p">:</span>
|
||
</pre></div>
|
||
</div>
|
||
<p>which would mean different things in Python 2.x and 3.x – leading to
|
||
hard-to-catch bugs – cannot legally occur in 3.x code.</p>
|
||
</section>
|
||
<section id="semantic-changes">
|
||
<h2><a class="toc-backref" href="#semantic-changes" role="doc-backlink">Semantic Changes</a></h2>
|
||
<p>In order to resolve the garbage collection issue related to <a class="pep reference internal" href="../pep-0344/" title="PEP 344 – Exception Chaining and Embedded Tracebacks">PEP 344</a>,
|
||
<code class="docutils literal notranslate"><span class="pre">except</span></code> statements in Python 3 will generate additional bytecode to
|
||
delete the target, thus eliminating the reference cycle.
|
||
The source-to-source translation, as suggested by Phillip J. Eby
|
||
<a class="footnote-reference brackets" href="#except-translation" id="id6">[5]</a>, is</p>
|
||
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="k">try</span><span class="p">:</span>
|
||
<span class="n">try_body</span>
|
||
<span class="k">except</span> <span class="n">E</span> <span class="k">as</span> <span class="n">N</span><span class="p">:</span>
|
||
<span class="n">except_body</span>
|
||
<span class="o">...</span>
|
||
</pre></div>
|
||
</div>
|
||
<p>gets translated to (in Python 2.5 terms)</p>
|
||
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="k">try</span><span class="p">:</span>
|
||
<span class="n">try_body</span>
|
||
<span class="k">except</span> <span class="n">E</span><span class="p">,</span> <span class="n">N</span><span class="p">:</span>
|
||
<span class="k">try</span><span class="p">:</span>
|
||
<span class="n">except_body</span>
|
||
<span class="k">finally</span><span class="p">:</span>
|
||
<span class="n">N</span> <span class="o">=</span> <span class="kc">None</span>
|
||
<span class="k">del</span> <span class="n">N</span>
|
||
<span class="o">...</span>
|
||
</pre></div>
|
||
</div>
|
||
<p>An implementation has already been checked into the py3k (formerly
|
||
“p3yk”) branch <a class="footnote-reference brackets" href="#translation-checkin" id="id7">[6]</a>.</p>
|
||
</section>
|
||
<section id="compatibility-issues">
|
||
<h2><a class="toc-backref" href="#compatibility-issues" role="doc-backlink">Compatibility Issues</a></h2>
|
||
<p>Nearly all <code class="docutils literal notranslate"><span class="pre">except</span></code> clauses will need to be changed. <code class="docutils literal notranslate"><span class="pre">except</span></code>
|
||
clauses with identifier targets will be converted from</p>
|
||
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="k">except</span> <span class="n">E</span><span class="p">,</span> <span class="n">N</span><span class="p">:</span>
|
||
</pre></div>
|
||
</div>
|
||
<p>to</p>
|
||
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="k">except</span> <span class="n">E</span> <span class="k">as</span> <span class="n">N</span><span class="p">:</span>
|
||
</pre></div>
|
||
</div>
|
||
<p><code class="docutils literal notranslate"><span class="pre">except</span></code> clauses with non-tuple, non-identifier targets
|
||
(e.g., <code class="docutils literal notranslate"><span class="pre">a.b.c[d]</span></code>) will need to be converted from</p>
|
||
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="k">except</span> <span class="n">E</span><span class="p">,</span> <span class="n">T</span><span class="p">:</span>
|
||
</pre></div>
|
||
</div>
|
||
<p>to</p>
|
||
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="k">except</span> <span class="n">E</span> <span class="k">as</span> <span class="n">t</span><span class="p">:</span>
|
||
<span class="n">T</span> <span class="o">=</span> <span class="n">t</span>
|
||
</pre></div>
|
||
</div>
|
||
<p>Both of these cases can be handled by Guido van Rossum’s <code class="docutils literal notranslate"><span class="pre">2to3</span></code>
|
||
utility <a class="footnote-reference brackets" href="#to3" id="id8">[7]</a> using the <code class="docutils literal notranslate"><span class="pre">except</span></code> fixer <a class="footnote-reference brackets" href="#exceptfixer" id="id9">[8]</a>.</p>
|
||
<p><code class="docutils literal notranslate"><span class="pre">except</span></code> clauses with tuple targets will need to be converted
|
||
manually, on a case-by-case basis. These changes will usually need
|
||
to be accompanied by changes to the exception classes themselves.
|
||
While these changes generally cannot be automated, the <code class="docutils literal notranslate"><span class="pre">2to3</span></code>
|
||
utility is able to point out cases where the target of an <code class="docutils literal notranslate"><span class="pre">except</span></code>
|
||
clause is a tuple, simplifying conversion.</p>
|
||
<p>Situations where it is necessary to keep an exception instance around
|
||
past the end of the <code class="docutils literal notranslate"><span class="pre">except</span></code> suite can be easily translated like so</p>
|
||
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="k">try</span><span class="p">:</span>
|
||
<span class="o">...</span>
|
||
<span class="k">except</span> <span class="n">E</span> <span class="k">as</span> <span class="n">N</span><span class="p">:</span>
|
||
<span class="o">...</span>
|
||
<span class="o">...</span>
|
||
</pre></div>
|
||
</div>
|
||
<p>becomes</p>
|
||
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="k">try</span><span class="p">:</span>
|
||
<span class="o">...</span>
|
||
<span class="k">except</span> <span class="n">E</span> <span class="k">as</span> <span class="n">N</span><span class="p">:</span>
|
||
<span class="n">n</span> <span class="o">=</span> <span class="n">N</span>
|
||
<span class="o">...</span>
|
||
<span class="o">...</span>
|
||
</pre></div>
|
||
</div>
|
||
<p>This way, when <code class="docutils literal notranslate"><span class="pre">N</span></code> is deleted at the end of the block, <code class="docutils literal notranslate"><span class="pre">n</span></code> will
|
||
persist and can be used as normal.</p>
|
||
<p>Lastly, all uses of the <code class="docutils literal notranslate"><span class="pre">sys</span></code> module’s <code class="docutils literal notranslate"><span class="pre">exc_type</span></code>, <code class="docutils literal notranslate"><span class="pre">exc_value</span></code>
|
||
and <code class="docutils literal notranslate"><span class="pre">exc_traceback</span></code> attributes will need to be removed. They can be
|
||
replaced with <code class="docutils literal notranslate"><span class="pre">sys.exc_info()[0]</span></code>, <code class="docutils literal notranslate"><span class="pre">sys.exc_info()[1]</span></code> and
|
||
<code class="docutils literal notranslate"><span class="pre">sys.exc_info()[2]</span></code> respectively, a transformation that can be
|
||
performed by <code class="docutils literal notranslate"><span class="pre">2to3</span></code>’s <code class="docutils literal notranslate"><span class="pre">sysexcattrs</span></code> fixer.</p>
|
||
<section id="compatibility">
|
||
<h3><a class="toc-backref" href="#compatibility" role="doc-backlink">2.6 - 3.0 Compatibility</a></h3>
|
||
<p>In order to facilitate forwards compatibility between Python 2.6 and 3.0,
|
||
the <code class="docutils literal notranslate"><span class="pre">except</span> <span class="pre">...</span> <span class="pre">as</span> <span class="pre">...:</span></code> syntax will be backported to the 2.x series. The
|
||
grammar will thus change from:</p>
|
||
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">except_clause</span><span class="p">:</span> <span class="s1">'except'</span> <span class="p">[</span><span class="n">test</span> <span class="p">[</span><span class="s1">','</span> <span class="n">test</span><span class="p">]]</span>
|
||
</pre></div>
|
||
</div>
|
||
<p>to:</p>
|
||
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="n">except_clause</span><span class="p">:</span> <span class="s1">'except'</span> <span class="p">[</span><span class="n">test</span> <span class="p">[(</span><span class="s1">'as'</span> <span class="o">|</span> <span class="s1">','</span><span class="p">)</span> <span class="n">test</span><span class="p">]]</span>
|
||
</pre></div>
|
||
</div>
|
||
<p>The end-of-suite cleanup semantic for <code class="docutils literal notranslate"><span class="pre">except</span></code> statements will not be
|
||
included in the 2.x series of releases.</p>
|
||
</section>
|
||
</section>
|
||
<section id="open-issues">
|
||
<h2><a class="toc-backref" href="#open-issues" role="doc-backlink">Open Issues</a></h2>
|
||
<section id="replacing-or-dropping-sys-exc-info">
|
||
<h3><a class="toc-backref" href="#replacing-or-dropping-sys-exc-info" role="doc-backlink">Replacing or Dropping “sys.exc_info()”</a></h3>
|
||
<p>The idea of dropping <code class="docutils literal notranslate"><span class="pre">sys.exc_info()</span></code> or replacing it with a
|
||
<code class="docutils literal notranslate"><span class="pre">sys.exception</span></code> attribute or a <code class="docutils literal notranslate"><span class="pre">sys.get_exception()</span></code> function
|
||
has been raised several times on python-3000 (<a class="footnote-reference brackets" href="#drop-excinfo" id="id10">[9]</a>,
|
||
<a class="footnote-reference brackets" href="#replace-excinfo" id="id11">[10]</a>) and mentioned in <a class="pep reference internal" href="../pep-0344/" title="PEP 344 – Exception Chaining and Embedded Tracebacks">PEP 344</a>’s “Open Issues” section.</p>
|
||
<p>While a <code class="docutils literal notranslate"><span class="pre">2to3</span></code> fixer to replace calls to <code class="docutils literal notranslate"><span class="pre">sys.exc_info()</span></code>
|
||
and some attribute accesses would be trivial, it would be far more
|
||
difficult for static analysis to find and fix functions that expect
|
||
the values from <code class="docutils literal notranslate"><span class="pre">sys.exc_info()</span></code> as arguments. Similarly, this does
|
||
not address the need to rewrite the documentation for all APIs that
|
||
are defined in terms of <code class="docutils literal notranslate"><span class="pre">sys.exc_info()</span></code>.</p>
|
||
</section>
|
||
</section>
|
||
<section id="implementation">
|
||
<h2><a class="toc-backref" href="#implementation" role="doc-backlink">Implementation</a></h2>
|
||
<p>This PEP was implemented in revisions 53342 <a class="footnote-reference brackets" href="#r53342" id="id12">[11]</a> and 53349
|
||
<a class="footnote-reference brackets" href="#r53349" id="id13">[12]</a>. Support for the new <code class="docutils literal notranslate"><span class="pre">except</span></code> syntax in 2.6 was
|
||
implemented in revision 55446 <a class="footnote-reference brackets" href="#r55446" id="id14">[13]</a>.</p>
|
||
</section>
|
||
<section id="references">
|
||
<h2><a class="toc-backref" href="#references" role="doc-backlink">References</a></h2>
|
||
<aside class="footnote-list brackets">
|
||
<aside class="footnote brackets" id="sys-module" role="doc-footnote">
|
||
<dt class="label" id="sys-module">[<a href="#id1">1</a>]</dt>
|
||
<dd><a class="reference external" href="http://docs.python.org/library/sys.html">http://docs.python.org/library/sys.html</a></aside>
|
||
<aside class="footnote brackets" id="firstproposal" role="doc-footnote">
|
||
<dt class="label" id="firstproposal">[2]<em> (<a href='#id3'>1</a>, <a href='#id4'>2</a>) </em></dt>
|
||
<dd><a class="reference external" href="https://mail.python.org/pipermail/python-dev/2006-March/062449.html">https://mail.python.org/pipermail/python-dev/2006-March/062449.html</a></aside>
|
||
<aside class="footnote brackets" id="renaming" role="doc-footnote">
|
||
<dt class="label" id="renaming">[<a href="#id5">3</a>]</dt>
|
||
<dd><a class="reference external" href="https://mail.python.org/pipermail/python-dev/2006-March/062640.html">https://mail.python.org/pipermail/python-dev/2006-March/062640.html</a></aside>
|
||
<aside class="footnote brackets" id="grammar" role="doc-footnote">
|
||
<dt class="label" id="grammar">[<a href="#id2">4</a>]</dt>
|
||
<dd><a class="reference external" href="http://docs.python.org/reference/compound_stmts.html#try">http://docs.python.org/reference/compound_stmts.html#try</a></aside>
|
||
<aside class="footnote brackets" id="except-translation" role="doc-footnote">
|
||
<dt class="label" id="except-translation">[<a href="#id6">5</a>]</dt>
|
||
<dd><a class="reference external" href="https://mail.python.org/pipermail/python-3000/2007-January/005395.html">https://mail.python.org/pipermail/python-3000/2007-January/005395.html</a></aside>
|
||
<aside class="footnote brackets" id="translation-checkin" role="doc-footnote">
|
||
<dt class="label" id="translation-checkin">[<a href="#id7">6</a>]</dt>
|
||
<dd><a class="reference external" href="http://svn.python.org/view?rev=53342&view=rev">http://svn.python.org/view?rev=53342&view=rev</a></aside>
|
||
<aside class="footnote brackets" id="to3" role="doc-footnote">
|
||
<dt class="label" id="to3">[<a href="#id8">7</a>]</dt>
|
||
<dd><a class="reference external" href="https://hg.python.org/sandbox/guido/file/2.7/Lib/lib2to3/">https://hg.python.org/sandbox/guido/file/2.7/Lib/lib2to3/</a></aside>
|
||
<aside class="footnote brackets" id="exceptfixer" role="doc-footnote">
|
||
<dt class="label" id="exceptfixer">[<a href="#id9">8</a>]</dt>
|
||
<dd><a class="reference external" href="https://hg.python.org/sandbox/guido/file/2.7/Lib/lib2to3/fixes/fix_except.py">https://hg.python.org/sandbox/guido/file/2.7/Lib/lib2to3/fixes/fix_except.py</a></aside>
|
||
<aside class="footnote brackets" id="drop-excinfo" role="doc-footnote">
|
||
<dt class="label" id="drop-excinfo">[<a href="#id10">9</a>]</dt>
|
||
<dd><a class="reference external" href="https://mail.python.org/pipermail/python-3000/2007-January/005385.html">https://mail.python.org/pipermail/python-3000/2007-January/005385.html</a></aside>
|
||
<aside class="footnote brackets" id="replace-excinfo" role="doc-footnote">
|
||
<dt class="label" id="replace-excinfo">[<a href="#id11">10</a>]</dt>
|
||
<dd><a class="reference external" href="https://mail.python.org/pipermail/python-3000/2007-January/005604.html">https://mail.python.org/pipermail/python-3000/2007-January/005604.html</a></aside>
|
||
<aside class="footnote brackets" id="r53342" role="doc-footnote">
|
||
<dt class="label" id="r53342">[<a href="#id12">11</a>]</dt>
|
||
<dd><a class="reference external" href="http://svn.python.org/view?view=revision&revision=53342">http://svn.python.org/view?view=revision&revision=53342</a></aside>
|
||
<aside class="footnote brackets" id="r53349" role="doc-footnote">
|
||
<dt class="label" id="r53349">[<a href="#id13">12</a>]</dt>
|
||
<dd><a class="reference external" href="http://svn.python.org/view?view=revision&revision=53349">http://svn.python.org/view?view=revision&revision=53349</a></aside>
|
||
<aside class="footnote brackets" id="r55446" role="doc-footnote">
|
||
<dt class="label" id="r55446">[<a href="#id14">13</a>]</dt>
|
||
<dd><a class="reference external" href="http://svn.python.org/view/python/trunk/?view=rev&rev=55446">http://svn.python.org/view/python/trunk/?view=rev&rev=55446</a></aside>
|
||
</aside>
|
||
</section>
|
||
<section id="copyright">
|
||
<h2><a class="toc-backref" href="#copyright" role="doc-backlink">Copyright</a></h2>
|
||
<p>This document has been placed in the public domain.</p>
|
||
</section>
|
||
</section>
|
||
<hr class="docutils" />
|
||
<p>Source: <a class="reference external" href="https://github.com/python/peps/blob/main/peps/pep-3110.rst">https://github.com/python/peps/blob/main/peps/pep-3110.rst</a></p>
|
||
<p>Last modified: <a class="reference external" href="https://github.com/python/peps/commits/main/peps/pep-3110.rst">2023-09-09 17:39:29 GMT</a></p>
|
||
|
||
</article>
|
||
<nav id="pep-sidebar">
|
||
<h2>Contents</h2>
|
||
<ul>
|
||
<li><a class="reference internal" href="#abstract">Abstract</a></li>
|
||
<li><a class="reference internal" href="#rationale">Rationale</a></li>
|
||
<li><a class="reference internal" href="#grammar-changes">Grammar Changes</a></li>
|
||
<li><a class="reference internal" href="#semantic-changes">Semantic Changes</a></li>
|
||
<li><a class="reference internal" href="#compatibility-issues">Compatibility Issues</a><ul>
|
||
<li><a class="reference internal" href="#compatibility">2.6 - 3.0 Compatibility</a></li>
|
||
</ul>
|
||
</li>
|
||
<li><a class="reference internal" href="#open-issues">Open Issues</a><ul>
|
||
<li><a class="reference internal" href="#replacing-or-dropping-sys-exc-info">Replacing or Dropping “sys.exc_info()”</a></li>
|
||
</ul>
|
||
</li>
|
||
<li><a class="reference internal" href="#implementation">Implementation</a></li>
|
||
<li><a class="reference internal" href="#references">References</a></li>
|
||
<li><a class="reference internal" href="#copyright">Copyright</a></li>
|
||
</ul>
|
||
|
||
<br>
|
||
<a id="source" href="https://github.com/python/peps/blob/main/peps/pep-3110.rst">Page Source (GitHub)</a>
|
||
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|
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