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quoting attribute values is a hard habit to break

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Mark Pilgrim
2009-05-20 17:34:24 -04:00
parent ab23b6b659
commit 52b451d753
11 changed files with 87 additions and 58 deletions
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regular-expressions.html
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@@ -295,7 +295,7 @@ body{counter-reset:h1 4}
<a><samp class=p>>>> </samp><kbd>phonePattern.search('800-555-1212-1234')</kbd> <span>&#x2462;</span></a>
<samp class=p>>>> </samp></pre>
<ol>
<li>Always read regular expressions from left to right. This one matches the beginning of the string, and then <code>(\d{3})</code>. What&#8217;s <code>\d{3}</code>? Well, the <code>{3}</code> means &#8220;match exactly three numeric digits&#8221;; it&#8217;s a variation on the <a href="#re.nm" title="7.4. Using the {n,m} Syntax"><code>{n,m} syntax</code></a> you saw earlier. <code>\d</code> means &#8220;any numeric digit&#8221; (<code>0</code> through <code>9</code>). Putting it in parentheses means &#8220;match exactly three numeric digits, <em>and then remember them as a group that I can ask for later</em>&#8221;. Then match a literal hyphen. Then match another group of exactly three digits. Then another literal hyphen. Then another group of exactly four digits. Then match the end of the string.
<li>Always read regular expressions from left to right. This one matches the beginning of the string, and then <code>(\d{3})</code>. What&#8217;s <code>\d{3}</code>? Well, the <code>{3}</code> means &#8220;match exactly three numeric digits&#8221;; it&#8217;s a variation on the <a href=#nmsyntax><code>{n,m} syntax</code></a> you saw earlier. <code>\d</code> means &#8220;any numeric digit&#8221; (<code>0</code> through <code>9</code>). Putting it in parentheses means &#8220;match exactly three numeric digits, <em>and then remember them as a group that I can ask for later</em>&#8221;. Then match a literal hyphen. Then match another group of exactly three digits. Then another literal hyphen. Then another group of exactly four digits. Then match the end of the string.
<li>To get access to the groups that the regular expression parser remembered along the way, use the <code>groups()</code> method on the object that the <code>search()</code> method returns. It will return a tuple of however many groups were defined in the regular expression. In this case, you defined three groups, one with three digits, one with three digits, and one with four digits.
<li>This regular expression is not the final answer, because it doesn&#8217;t handle a phone number with an extension on the end. For that, you&#8217;ll need to expand the regular expression.
</ol>