LoTROInterface SVN KragenBars

-- Class.lua

-- Compatible with Lua 5.1 (not 5.0).

--

-- Modified to use a metatable to reference base objects instead

-- or performing shallow copies. This means smaller classes that

-- are a bit more dynamic at the expence of some performance.

_G.class = function( base )

        if ( base ~= nil ) then

                local baseType = type( base );

                if ( baseType ~= 'table' ) then

                        error( "Base class is not a table. Base class was a " .. baseType );

                end

        end

        -- The class definition table. Contains all of the actual class

        -- methods, constructor, and an IsA function automatically

        -- provided.

        local c  = { };

        c.base = base;

        c.IsA = function( self, klass )

                local m = getmetatable( self );

                while m do

                        if m == klass then

                                return true;

                        end

                        m = m.base;

                end

                return false;

        end

        -- The class definition metatable. This is used to hook up

        -- base classes and then to register a call handler that is

        -- used to construct new instances of the class.

        local mt = { };

        mt.__index = base;

        mt.__call = function( class_tbl, ... )

                if ( class_tbl.Abstract ) then

                        error "Abstract class cannot be constructed.";

                end

                -- Create the new class instance.

                local instance = { };

                setmetatable( instance, { __index = c } );

                -- Invoke the constructor if it exists.

                if ( ( instance.Constructor ~= nil ) and ( type( instance.Constructor ) == 'function' ) ) then

                        instance:Constructor( ... );

                end

                return instance;

        end

        setmetatable( c, mt );

        return c;

end