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two more 2to3 sections, fixed TOC

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This commit is contained in:
Mark Pilgrim
2009-01-31 08:21:30 -05:00
parent d291398286
commit 92af142439
2 changed files with 69 additions and 66 deletions
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porting-code-to-python-3-with-2to3.html
+14 -15
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@@ -9,7 +9,6 @@
h1:before{counter-increment:h1;content:"Appendix A. "}
h2:before{counter-increment:h2;content:"A." counter(h2) ". "}
h3:before{counter-increment:h3;content:"A." counter(h2) "." counter(h3) ". "}
td{font-family:monospaced}
</style>
</head>
<body>
@@ -674,7 +673,7 @@ except:
<p>You should never use a fallback to catch <em>all</em> exceptions when importing modules (or most other times). Doing so will catch things like <code>KeyboardInterrupt</code> (if the user pressed <kbd>Ctrl-C</kbd> to interrupt the program) and can make it more difficult to debug errors.
</blockquote>
<h2 id="raise"><code>raise</code> statement</h2>
<p>FIXME intro
<p>The syntax for raising your own exceptions has changed slightly between Python 2 and Python 3.
<p class="skip"><a href="#skipcompareraise">skip over this table</a>
<table id="compareraise">
<tr><th>Notes</th>
@@ -682,19 +681,23 @@ except:
<th>Python 3</th>
</tr>
<tr><th>&#x2460;</th>
<td><code>raise MyException</code></td>
<td><i>unchanged</i></td></tr>
<tr><th>&#x2461;</th>
<td><code>raise MyException, "error message"</code></td>
<td><code>raise MyException("error message")</code></td></tr>
<tr><th>&#x2461;</th>
<tr><th>&#x2462;</th>
<td><code>raise MyException, "error message", a_traceback</code></td>
<td><code>raise MyException("error message").with_traceback(a_traceback)</code></td></tr>
<tr><th>&#x2462;</th>
<tr><th>&#x2463;</th>
<td><code>raise "error message"</code></td>
<td><i>unsupported</i></td></tr>
</table>
<ol id="skipcompareraise">
<li>...
<li>...
<li>...
<li>In the simplest form, raising an exception without a custom error message, the syntax is unchanged.
<li>The change becomes noticeable when you want to raise an exception with a custom error message. Python 2 separated the exception class and the message with a comma; Python 3 passes the error message as a parameter.
<li>Python 2 supported a more complex syntax to raise an exception with a custom traceback (stack trace). You can do this in Python 3 as well, but the syntax is quite different.
<li>In Python 2, you could raise an exception with no exception class, just an error message. In Python 3, this is no longer possible. <code>2to3</code> will warn you that it was unable to fix this automatically.
</ol>
<h2 id="throw"><code>throw</code> statement</h2>
<p>FIXME intro
@@ -751,7 +754,7 @@ except:
<li>The <code>sum()</code> function will also work with an iterator, so <code>2to3</code> makes no changes here either. Like <a href="#dict">dictionary methods that return views instead of lists</a>, this applies to <code>min()</code>, <code>max()</code>, <code>sum()</code>, <code>list()</code>, <code>tuple()</code>, <code>set()</code>, <code>sorted()</code>, <code>any()</code>, and <code>all()</code>.
</ol>
<h2 id="raw_input"><code>raw_input()</code> and <code>input()</code> global functions</h2>
<p>FIXME intro
<p>Python 2 had two global functions for asking the user for input on the command line. The first, called <code>input()</code>, expected the user to enter a Python expression (and returned the result). The second, called <code>raw_input()</code>, just returned whatever the user typed. This was wildly confusing for beginners and wildly regarded as a &#8220;wart&#8221; in the language. Python 3 excises this wart by renaming <code>raw_input()</code> to <code>input()</code>, so it works the way everyone naively expects it to work.
<p class="skip"><a href="#skipcompareraw_input">skip over this table</a>
<table id="compareraw_input">
<tr><th>Notes</th>
@@ -767,15 +770,11 @@ except:
<tr><th>&#x2462;</th>
<td><code>input()</code></td>
<td><code>eval(input())</code></td></tr>
<tr><th>&#x2463;</th>
<td><code>input("prompt")</code></td>
<td><code>eval(input("prompt"))</code></td></tr>
</table>
<ol id="skipcompareraw_input">
<li>...
<li>...
<li>...
<li>...
<li>In the simplest form, <code>raw_input()</code> becomes <code>input()</code>.
<li>In Python 2, the <code>raw_input()</code> function could take a prompt as a parameter. This has been retained in Python 3.
<li>If you actually need to ask the user for a Python expression to evaluate, use the <code>input()</code> function and pass the result to <code>eval()</code>.
</ol>
<h2 id="funcattrs"><code>func_*</code> function attributes</h2>
<p>FIXME intro