First commit.

src/utils/classes.lua

@@ -0,0 +1,50 @@
+------------------------------------------------------------------------------
+-- Methods
+------------------------------------------------------------------------------
+
+--- Code from http://lua-users.org/wiki/ObjectOrientationTutorial
+---@param ... table Optional base classes
+---@return table cls A class definition
+local function make_class(...)
+    -- "cls" is the new class
+    local cls, bases = {}, {...}
+
+    -- copy base class contents into the new class
+    for _, base in ipairs(bases) do
+        for k, v in pairs(base) do
+            cls[k] = v
+        end
+    end
+
+    -- set the class's __index, and start filling an "is_a" table that contains this class and all of its bases
+    -- so you can do an "instance of" check using my_instance.is_a[MyClass]
+    cls.__index, cls.is_a = cls, {[cls] = true}
+
+    for _, base in ipairs(bases) do
+        for c in pairs(base.is_a) do
+            cls.is_a[c] = true
+        end
+        cls.is_a[base] = true
+    end
+
+    -- the class's __call metamethod
+    setmetatable(cls, {__call = function (c, ...)
+        local instance = setmetatable({}, c)
+
+        -- run the init method if it's there
+        local init = instance._init
+
+        if init then init(instance, ...) end
+        return instance
+    end})
+
+    -- return the new class table, that's ready to fill with methods
+    return cls
+end
+
+
+------------------------------------------------------------------------------
+-- Module return
+------------------------------------------------------------------------------
+
+return make_class