modules.on_module_unload

Defined in module "modules"

from "modules" import on_module_unload

on_module_unload(arg1: function): any

Register module unload callback. Example: on_module_unload( function(is_app_closing) {println(is_app_closing ? "Closing" : "Soft reloading")} )

This function is bound with a type mask instead of a declaration string. The VM cannot report parameter names, and cannot tell an optional parameter from a variadic tail, so the brackets and the trailing ... above are not evidence either way.

Parameters

arg1 function arg1([is_app_closing]), the callback to run. This function is bound with a type mask instead of a declaration string, so the VM cannot report the real parameter name; arg1 is the callback, not a value passed to it.

Return value

null.

Errors

Throws when the callback takes more than one argument (besides this): a registered callback must accept zero or one argument.

Notes

The callback runs later, not immediately: once when the module manager is destroyed (typically at process exit), with is_app_closing set to true, and also once before a hot reload of a module or of all modules, with is_app_closing set to false. Callbacks run in the order they were registered.

Registering the exact same function object a second time has no extra effect: only one call happens per distinct callback, however many times it was registered.

Example

examples/modules/on_module_unload.nut

let modules = require("modules")

// Runs when this script's module manager is torn down: normally at process
// exit, or before a script is hot-reloaded during development.
modules.on_module_unload(function(is_app_closing) {
  println($"unload, is_app_closing={is_app_closing}")
})

println("script body done")
// Nothing else to do: the callback above fires after this, when the host
// closes the VM, so its output always comes last.

Output:

script body done
unload, is_app_closing=true