option

The option parameter type uses a table to populate a list of strings in the PARAMETERS menu, like when a script wants to know which MIDI device to send data to:

function init()
  midi_device_names = {}
  for i = 1,#midi.vports do
    midi_device_names[i] = i..": "..midi.vports[i].name
  end
  
  params:add{
    type = "option",
    id = "target_midi_device",
    name = "MIDI target",
    options = midi_device_names,
    default = 1,
    action = function(id) out_device = midi.connect(id) end
  }
  
  params:bang() -- this creates var 'out_device' and connects it to port 1
  
end

Note that in this example, we’ve declared an action which is called when the parameter changes values. We also used params:bang() to force out_device into existence and connect it to port 1 as a default.

Like with our number example, we can also declare our option parameter by using params:add_option:

function init()
  midi_device_names = {}
  for i = 1,#midi.vports do
    midi_device_names[i] = i..": "..midi.vports[i].name
  end
  
  params:add_option("target_midi_device", "MIDI target", midi_device_names, 1)
  params:set_action("target_midi_device", function(id) out_device = midi.connect(id) end)
  
  params:bang() -- this creates var 'out_device' and connects it to port 1
  
end

Note that using this type of helper requires a separate set_action declaration if we want to assign an action to occur when the parameter changes values.

We have two ways of querying the value of this parameter type. To get the index of the table:

>> params:get("target_midi_device")

To get the string that’s presented in the PARAMETERS menu:

>> params:string("target_midi_device")

This parameter type responds to E3 in the PARAMETERS menu.