From 5fac39307dc75586d93e69920c4b837e277f0c85 Mon Sep 17 00:00:00 2001 From: Robert Hensing Date: Sun, 16 Apr 2023 19:25:09 +0200 Subject: module-system.chapter.md: Add mental model to `type` and `extendModules` --- doc/module-system/module-system.chapter.md | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'doc') diff --git a/doc/module-system/module-system.chapter.md b/doc/module-system/module-system.chapter.md index 2f19096577fd..2f9716c89dbc 100644 --- a/doc/module-system/module-system.chapter.md +++ b/doc/module-system/module-system.chapter.md @@ -64,12 +64,17 @@ The option definitions that are typed with this type will extend the current set However, the value returned from the type is just the [`config`](#module-system-lib-evalModules-return-value-config), like any submodule. +If you're familiar with prototype inheritance, you can think of this `evalModules` invocation as the prototype, and usages of this type as the instances. + This type is also available to the [`modules`](#module-system-lib-evalModules-param-modules) as the module argument `moduleType`. + #### `extendModules` {#module-system-lib-evalModules-return-value-extendModules} A function similar to `evalModules` but building on top of the already passed [`modules`](#module-system-lib-evalModules-param-modules). Its arguments, `modules` and `specialArgs` are added to the existing values. +If you're familiar with prototype inheritance, you can think of the current, actual `evalModules` invocation as the prototype, and the return value of `extendModules` as the instance. + The real work of module evaluation happens while computing the values in `config` and `options`, so multiple invocations of `extendModules` have a particularly small cost, as long as only the final `config` and `options` are evaluated. If you do reference multiple `config` (or `options`) from before and after `extendModules`, evaluation performance is the same as with multiple `evalModules` invocations, because the new modules' ability to override existing configuration fundamentally requires constructing a new `config` and `options` fixpoint. -- cgit 1.4.1