Refactoring: add base_classes.Event class. Relates to lord-server#1558

mods/lord/Core/base_classes/init.lua

@@ -0,0 +1,5 @@
+
+
+minetest.mod(function(mod)
+	require("base_classes").init(mod)
+end)

mods/lord/Core/base_classes/mod.conf

@@ -0,0 +1,5 @@
+name = base_classes
+title = Base Classes
+description = Very handly common base classes to make life easier
+depends = builtin
+author = alek13

mods/lord/Core/base_classes/src/base_classes.lua

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+local Event = require("base_classes.Event")
+
+
+base_classes = {} -- luacheck: ignore unused global variable base_classes
+
+local function register_api()
+	_G.base_classes = {
+		Event = Event
+	}
+end
+
+
+return {
+	init = function()
+		register_api()
+	end,
+}

mods/lord/Core/base_classes/src/base_classes/Event.lua

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+local pairs
+    = pairs
+
+
+--- @static
+--- @class base_classes.Event
+local Event = {
+	Type        = {},
+	subscribers = {},
+}
+
+--- @static
+--- @return base_classes.Event
+function Event:extended(object_or_class)
+	local class = self
+	self = object_or_class or {}
+	return setmetatable(self, { __index = class} )
+end
+
+
+--- @alias base_classes.Event.callback function
+
+--- @param event string name of event (One of `Event.Type::<const>`)
+---
+--- @return fun(callback:controls.callback)
+function Event:on(event)
+	return function(callback)
+		self:subscribe(event, callback)
+	end
+end
+
+--- @param event    string name of event (One of `Event.Type::<const>`)
+--- @param callback controls.callback
+function Event:subscribe(event, callback)
+	assert(self.Type[event], "Unknown controls.Event.Type: " .. event)
+	assert(type(callback) == "function")
+
+	table.insert(self.subscribers[event], callback)
+end
+
+--- @private
+--- @param event string name of event (One of `Event.Type::<const>`)
+--- @vararg any pass args that will be passed to subscribers callbacks. See `controls.callbacks.<func-types>`
+function Event:notify(event, ...)
+	assert(self.Type[event], "Unknown controls.Event.Type: " .. event)
+
+	for _, func in pairs(self.subscribers[event]) do
+		func(...)
+	end
+end
+
+--- @param event string name of event (One of `Event.Type::<const>`)
+--- @vararg any pass args that will be passed to subscribers callbacks. See `controls.callbacks.<func-types>`
+function Event:trigger(event, ...)
+	self:notify(event, ...)
+end
+
+
+return Event