To do that, follow the GraalVM install instructions to install a Java 17 or later version. The Java 17 version is recommended. Note that using Java 17 will cause some problems for other JMRI functions, see the description of those.
Next, check that "python" has been installed in your GraalVM using the command
gu list
If the gu command is not available, it's likely that your GraalVM installation
didn't go correctly. If that command doesn't show "python" installed, you have
to install it:
gu install python
then check again with the gu list command.
Once you do all that and start JMRI, a "Python 3" choice should appear in the language selector in the Script Input Window, and the file choosers for running scripts should give you a similar choice.
Our convention is that Python 3 files use a .py3 extension.
print (123)
there are some scripting-related differences:
import jmri as jmri
import java
exec( open("jython/jmri_bindings.py3").read() )
The third line is the Py3 syntax to read and execute another script file.
In this case, it reads and executes the file that defines a number of
symbols like `THROWN``, `turnouts`, etc.
manager = jmri.InstanceManager.getNullableDefault('jmri.MyManager')
(note quotes). More generally, if you need access to a Java type
object for other purposes, you can get it with
java.type('jmri.MyManager')
but we've provided a new version of InstanceManager.getDefault and
InstanceManager.getNullableDefault that takes the class name as
a parameter to make those common operations simpler.
DigitalIO.ON, not Light.ON.
class Automat(AbstractAutomaton) :
def init(self) :
print ("init in Python 3")
def handle(self) :
print ("handle in Python 3")
return False