MediaWiki extension

Among the most popular extensions is a parser function extension, ParserFunctions, that allows different content to be rendered based on the result of conditional statements. These conditional statements can perform functions such as evaluating whether a parameter is empty, comparing strings, evaluating mathematical expressions, and returning one of two values depending on whether a page exists. It was designed as a replacement for a notoriously inefficient template called {{Qif}}. Schindler recounts the history of the ParserFunctions extension as follows:

...
Wikipedia