How to check for key existence in a table (for the lazy programmer) ?

[Bertrand Mansion <lua@...>]

In Lua programs, I often see code like the following:

  if host.devices and host.devices.bridge and host.devices.bridge.friendlyName then

In Php, I have seen this:

  if (isset($host['devices']['bridge']['friendlyName']))


In Python, I have seen this:

  try:
    if host['devices']['bridge']['friendlyName']:
      ...
  except KeyError:
    pass

Are there other ways in Lua to check for a key existence ?