Howto:Create a new system in Nasal

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Status: Planning

Last updated: 12/2010

Authors: Hooray

References:

This tutorial will document all the steps involved in creating a new Nasal module that constantly updates itself, Nasal is FlightGear's scripting language. This tutorial is based on Howto: Create a new Nasal module, you should fully understand that one first.

• create a new plain text file under $FG_ROOT/Nasal/MODULE.nas
• replace MODULE with the name for your new module (for example, use "test")
• paste the following code into this file using a text editor (such as notepad on Windows)

# test.nas (save in $FG_ROOT/Nasal)
var mycode = func {
  print("running mycode() ");
  settimer(mycode, 3); # register a timer, invoke the "mycode" function again after 3 seconds
}

_setlistener("/sim/signals/nasal-dir-initialized", mycode);

This piece of code defines a new function named "mycode" that just prints a message to the console. Next, a timer is registered to invoke the mycode function again after 3 seconds have passed.

The _selistener call at the end of the snippet waits for the Nasal system to be initialized before the "mycode" function gets called.