Lua tips & tricks

This page contains some lua tips & tricks that might be you creating better code and instruments

Inline functions

Lua allows you to create inline functions. With the function inline you can reduce code and keep things more organized. Below you will find an example without and one with function inlining.

-- Typical way for a callback
  function callback()
    print("Button has been pressed")
  end
  button_add("pressed.png", "released.png", 0, 0, 256, 256, callback)


  -- Inline the callback
  button_add("pressed.png", "released.png", 0, 0, 256, 256, function()
    print("Button has been pressed")
  end)

You can apply this trick with all API functions that require a callback function, like timer_start, xpl_dataref_subscribe, fsx_variable_subscribe, etc. etc.)

Inline boolean statements

You can reduce code when inlining your boolean statements. See example below.

-- Typical way
  value = 12
  if value > 2 then
    visible(txt_id, true)
  else
    visible(txt_id, false)
  end

  -- Inline
  visible(txt_id, value > 2)

-- Combining multiple variables
  some_value = 12
  some_boolean = true
  some_state = "INIT"

  visible(txt_id, ( (some_value > 2) and some_boolean) or (some_state == "INIT") )