Serge NOEL
46 lines
1.6 KiB
Markdown
46 lines
1.6 KiB
Markdown
The jython/test/Python3Test.py3 provides some examples of these.
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You can access jmri.Turnout.CLOSED but jmri.Turnout.UNKNOWN is undefined. You have to access jmri.NamedBean.UNKNOWN instead, which is a real pain.
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The Jython property wrapper syntax that makes the next two lines the same is not available:
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```
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turnout.state
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turnout.getState()
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```
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Some Java super-class methods of a Python class need to be called via e.g.
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```
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self.__super__.waitMsec(1000)
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```
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But others don’t, and it’s not clear why.
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Referencing Python local variables in a Java-based object requires .this. syntax:
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```
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m = MyListener()
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#
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# invoked the listener, which sets 'internalVariable'
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#
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m.this.internalVariable
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```
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We can't yet put JMRI symbols into the Python context, so you have to run
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```
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exec(open("jython/jmri_bindings.py3").read())
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```
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at the start of each script. This provides definitions for the usual symbols: ON, OFF, ACTIVE, turnouts, sensors etc.
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Referencing a class type needs a java.type wrapper:
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```
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sm = jmri.InstanceManager.getNullableDefault(java.type('jmri.SensorManager'))
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```
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We've put a helper method in place for that specific case
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```
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sm = jmri.InstanceManager.getNullableDefault('jmri.SensorManager')
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```
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but you may need the `java.type('jmri.SensorManager')` syntax in other places.
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The debugging support is terrible: Syntax errors generate opaque error messages that don’t point to the relevant line in the script.
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AbstractAutomaton subclasses occasionally cause the whole of JMRI to stop with a thread deadlock. Not understood why the GraalVM Python interpreter is occasionally taking a lock on the Swing/AWT thread.
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