How Quickload Plugins Work and Writing Library Scripts

executed. The second time the script is loaded "s:did_load" exists and the commands after the "endif" are executed. This defines the (possible long) BufNetRead() and BufNetWrite() functions. If you drop this script in your plugin directory Vim will execute it on startup. This is the sequence of events that happens: 1. The "BNRead" command is defined and the <F19> key is mapped when the script is sourced at startup. A |FuncUndefined| autocommand is defined. The ":finish" command causes the script to terminate early. 2. The user types the BNRead command or presses the <F19> key. The BufNetRead() or BufNetWrite() function will be called. 3. Vim can't find the function and triggers the |FuncUndefined| autocommand event. Since the pattern "BufNet*" matches the invoked function, the command "source fname" will be executed. "fname" will be equal to the name of the script, no matter where it is located, because it comes from expanding "<sfile>" (see |expand()|). 4. The script is sourced again, the "s:did_load" variable exists and the functions are defined. Notice that the functions that are loaded afterwards match the pattern in the |FuncUndefined| autocommand. You must make sure that no other plugin defines functions that match this pattern. ============================================================================== *41.15* Writing library scripts *write-library-script* Some functionality will be required in several places. When this becomes more than a few lines you will want to put it in one script and use it from many scripts. We will call that one script a library script. Manually loading a library script is possible, so long as you avoid loading it when it's already done. You can do this with the |exists()| function. Example: > if !exists('*MyLibFunction') runtime library/mylibscript.vim endif call MyLibFunction(arg) Here you need to know that MyLibFunction() is defined in a script "library/mylibscript.vim" in one of the directories in 'runtimepath'. To make this a bit simpler Vim offers

This section explains how quickload plugins work. The script is first loaded to define commands and mappings. When a command or mapping is used, Vim can't find the associated function, triggering a `FuncUndefined` autocommand. This causes the script to be sourced again, defining the functions. The section also introduces library scripts, which contain functionality used in multiple places. It describes manually loading a library script using `runtime` and `exists()` to avoid loading it multiple times.