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POIndenting for code-generation
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copied!<p>Often, programmers write code that generates other code.</p> <p>(The technical term is <a href="http://en.wikipedia.org/wiki/Metaprogramming" rel="nofollow noreferrer" title="Wikipedia article on metaprogramming">metaprogramming</a>, but it is more common than merely cross-compilers; think about every PHP web-page that generates HTML or every XSLT file.)</p> <p>One area I find challenging is coming up with techniques to ensure that <em>both</em> the hand-written source file, and the computer-generated object file are clearly indented to aid debugging. The two goals often seem to be competing.</p> <p>I find this particularly challenging in the PHP/HTML combination. I think that is because:</p> <ul> <li>there is sometimes more of the HTML code in the source file than the generating PHP</li> <li>HTML files tend to be longer than, say, SQL statements, and need better indenting</li> <li>HTML has space-sensitive features (e.g. between tags)</li> <li>the result is more publicly visible HTML than SQL statements, so there is more pressure to do a reasonable job.</li> </ul> <p>What techniques do you use to address this?</p> <p><hr/> Edit: I accept that there are at least three arguments to not bothering to generate pretty HTML code:</p> <ul> <li>Complexity of generating code is increased.</li> <li>Makes no difference to rendering by browser; developers can use Firebug or similar to view it nicely.</li> <li>Minor performance hit - increased download time for whitespace characters.</li> </ul> <p>I have certainly sometimes generated code without thought to the indenting (especially SQL).</p> <p>However, there are a few arguments pushing the other way:</p> <ul> <li>I find, in practice, that I <em>do</em> frequently read generated code - having extra steps to access it is inconvenient.</li> <li>HTML has some space-sensitivity issues that bite occasionally. </li> </ul> <p>For example, consider the code:</p> <pre><code><div class="foo"> <?php $fooHeader(); $fooBody(); $fooFooter(); ?> </div> </code></pre> <p>It is clearer than the following code:</p> <pre><code><div class="foo"><?php $fooHeader(); $fooBody(); $fooFooter(); ?></div> </code></pre> <p>However, it is also has different rendering because of the whitespace included in the HTML.</p>

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