Promise functions to native libraries, that can be redefined at any point

PromisedFunctions.lua

--[[
	Virtual functions - Lua
]]

local vfunc = { }

function PromiseVirtualFunction( sFunctionName )
	return function( ... )
		if (vfunc[sFunctionName]) return vfunc[sFunctionName]( ... ) end
		error( string.format( "Promised function %s was nil", sFunctionName ) )
	end
end

function DefinePromisedFunction( sFunctionName, func )
	vfunc[sFunctionName] = func
end

-- Example use

timer.Simple( 1, PromiseVirtualFunction( "MyPromisedFunction" ))
DefinePromisedFunction( "MyPromisedFunction", function() print("Hello from promised function") end)