Enhance class definition: add inherit method to support base class inheritance

oop/oop.lua

@@ -70,6 +70,16 @@ function oop.class(def, base)
     function cls.setattr(target, key, value)
         return oop.setattr(target, key, value)
     end
+    function cls.inherit(parent)
+        cls.__base = parent
+        cls.super = parent
+        local mt = getmetatable(cls) or {}
+        mt.__index = parent
+        mt.__call = mt.__call or function(c, ...)
+            return oop.new(c, ...)
+        end
+        setmetatable(cls, mt)
+    end
 
     setmetatable(cls, {
         __index = base,
@@ -85,6 +95,9 @@ function oop.class(def, base)
     elseif def ~= nil then
         error("class definition must be a function or name string")
     end
+    if base then
+        cls.inherit(base)
+    end
 
     return cls
 end