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copied!<p>In <em><a href="http://amzn.com/0321334876" rel="noreferrer">Effective C++</a></em>, Scott Meyers notes in Item 2:</p> <blockquote> <p>Prefer <code>consts</code>, <code>enums</code>, and <code>inlines</code> to <code>#defines</code></p> </blockquote> <p>Specifically referring to the practice of writing macros instead of functions, Meyers says:</p> <blockquote> <p>Another common (mis)use of the <code>#define</code> directive is using it to implement macros that look like functions but don't incur the overhead of a function call.</p> <p>Macros like this have so many drawbacks, just thinking about them is painful.</p> <p>Fortunately, you don't have to put up with this nonsense. You can get all the efficiency of a macro plus all the predictable behavior and type safety of a regular function by using a template for an inline function.</p> <p>[Real functions] obey scope and access rules. For example, it makes perfect sense to talk about an inline function that is private to a class. In general, there's just no way to do that with a macro.</p> </blockquote> <p>To answer your questions specifically:</p> <ul> <li>Some programmers write macros instead of functions to avoid the perceived overhead of a function call -- a dubious practice that often has little measurable benefit. </li> <li>Programmers used to use the preprocessor to generate boilerplate code (and perhaps still do). In modern C++, use of the processor should be limited to <code>#include</code> and (maybe) <code>#ifdef</code>/<code>#ifndef</code> for conditional compilation. </li> </ul> <p>As Meyers notes in closing:</p> <blockquote> <p>It's not yet time to retire the preprocessor, but you should definitely give it long and frequent vacations.</p> </blockquote>

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