event = {}
event.__index = event
function event.__call(self, name, command)
-- eventChatCommand
print(string.format('%s triggered the command "%s".', name, command))
end

eventChatCommand = setmetatable({}, event)
eventChatCommand('Athesdrake#0000', 'test') -- working

-- [Athesdrake#0000] !test → not working

event = {}
event.__index = event
function event.__call(self, name, command)
-- eventChatCommand
print(string.format('%s triggered the command "%s".', name, command))
end

function dummy(func)
	return function(...) return func(...) end
end

eventChatCommand = dummy(setmetatable({}, event))
eventChatCommand('Athesdrake#0000', 'test') -- working

-- [Athesdrake#0000] !test → working !!

-- So now I can do something like that:
function event:test()
	print('Working !')
end

tfm.get.eventMetatable = setmetatable({}, event)
eventChatCommand = dummy(tfm.get.eventMetatable)

tfm.get.eventMetatable:test() -- Working !
-- Edit: I think this way is better:
_eventChatCommand = setmetatable({}, event)
eventChatCommand = dummy(_eventChatCommand)

_eventChatCommand:test() -- Working !