Software Architect's Handbook

Magic strings

Magic strings are strings that appear directly in your code. Sometimes, these strings are needed in multiple places and are duplicated, violating the DRY principle. Maintenance of these strings can become a nightmare because if you want to change the value of the string, you have to change it in multiple places. The problem is exacerbated when the string is used, not just in multiple places within the same class, but within multiple classes.

There are many examples of magic strings, from exception messages, settings in configuration files, parts of a file path, or a web URL. Let's look at an example where the magic string value represents a cache key. This serves as a good example because this is a case where a magic string ...