Scripting the Vim editor, Part 2: User-defined functions

Scripting the Vim editor, Part 2: User-defined functions: "User-defined functions are an essential tool for decomposing an application into correct and maintainable components, in order to manage the complexity of real-world programming tasks. This article (the second in a series) explains how to create and deploy new functions in the Vimscript language, giving several practical examples of why you might want to."