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author | Robert Hensing <robert@roberthensing.nl> | 2023-04-16 19:44:18 +0200 |
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committer | Robert Hensing <robert@roberthensing.nl> | 2023-05-06 18:32:58 +0200 |
commit | 8f02e95aff2b9cb94470ec379e2a3f55858cb03d (patch) | |
tree | 0a32286e09ef91dee4b9967a546f3ebc18dbe040 /doc/module-system | |
parent | 5fac39307dc75586d93e69920c4b837e277f0c85 (diff) |
module-system.chapter.md: Elaborate on extendModules performance
Diffstat (limited to 'doc/module-system')
-rw-r--r-- | doc/module-system/module-system.chapter.md | 13 |
1 files changed, 11 insertions, 2 deletions
diff --git a/doc/module-system/module-system.chapter.md b/doc/module-system/module-system.chapter.md index 2f9716c89dbc6..9a24ab70c6c17 100644 --- a/doc/module-system/module-system.chapter.md +++ b/doc/module-system/module-system.chapter.md @@ -75,11 +75,20 @@ A function similar to `evalModules` but building on top of the already passed [` 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. +This functionality is also available to modules as the `extendModules` module argument. + +::: {.note} + +**Evaluation Performance** + +`extendModules` returns a configuration that shares very little with the original `evalModules` invocation, because the module arguments may be different. + +So if you have a configuration that has been (or will be) largely evaluated, almost none of the computation is shared with the configuration returned by `extendModules`. + 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. - -This functionality is also available to modules as the `extendModules` module argument. +::: #### `_module` {#module-system-lib-evalModules-return-value-_module} |