The 'On GoSub' statement exists in Gambas since version 3.2.

Jumps to one of the calculated labels. The evaluation of 'Expression' must result in an integer value to select a (target) label. If there is a return statement in the instructions after the target(-Label), the program returns to execute the code immediately after the 'On GoSub' statement.

On Expression GoSub Label_0 [ , Label_1 ... ]
Instruction(s) -> program continuation after RETURN

Label_0:
  Instruction(s)_0
  RETURN
Label_1:
  Instruction(s)_1
  RETURN
…

• If the expression results in 0, then the first label is selected, if the expression has the value 1, then the second label is selected and so on…. .
• If the expression is negative or equal to or greater than the number of labels, then the 'On GoSub' instruction is tacitly ignored.
• To return to Label_x: after the instructions under the calculated target(-Label) Label_x: to *, you must use the Return statement - standing alone on one line.