Question

Ruby has this very interesting functionality in which when you create a class with ‘Class.new’ and assign it to a constant (uppercase), the language “magically” sets up the name of the class so it matches the constant.

# This is ruby code
MyRubyClass = Class.new(SuperClass)
puts MyRubyClass.name # "MyRubyClass"

It seems ruby “captures” the assignment and inserts sets the name on the anonymous class.

I’d like to know if there’s a way to do something similar in Lua.

I’ve implemented my own class system, but for it to work I’ve got to specify the same name twice:

-- This is Lua code
MyLuaClass = class('MyLuaClass', SuperClass)
print(MyLuaClass.name) -- MyLuaClass

I’d like to get rid of that 'MyLuaClass' string. Is there any way to do this in Lua?

Answer 1

When assigning to global variables you can set a __newindex metamethod for the table of globals to catch assignments of class variables and do whatever is needed.