G attribute for AbstractDetector - 12.2 release breaking change

Orekit Python Wrapper usage
1

Hello !

I used to work on Orekit 11.3.3 but I just moved to Orekit 12.2 with the Python Wrapper

I noticed some changes that impacted my software but one of them is unexpected:

In 12.2 the AbstractDectector class still inherits from the EventDetector class so I do not understand why I raise the error :

AttributeError: ‘AbstractDetector’ object has no attribute ‘g’

I saw here : Orekit [JCC] 12.2 released - breaking changes that the method finish had issues with the pthon wrapper is it the same for g ?

[Edit] : I have the same issue with KeplerianPropagator class which doesn’t know the attribute getPVCoordinatesinherited from AbstractPropagator

Thanks a lot

Augustin

3

Hi there and welcome,

With the JCC version, you need to use cast_ on the object each time you use a method that in Java is implemented in a parent class (you’ll find many example on the forum, not using it is the source of many AttributeError).

So for getPVCoordinates, try “casting” as AbstractPropagator or AbstractAnalyticalPropagator (I’ve not checked the code to see which one)

For the g function of events, it’s weird. What detector exactly are you using?

Cheers,
Romain.

1 Like
4

Hi and welcome @AugustinG,

The abstract method g(...) was removed from AbstractDetector since it was useless (already defined in interface EventDetector).
Technically it’s not an API breaking change in Java, but it looks like it is with the Python wrapper. Maybe we need to strengthen our policy and the scope of “API breaking changes” for minor releases and patches.
Anyway, I think that the casting you need to perform now is with EventDetector instead of the abstract subclass. Or PythonEventDetector ? I’m not sure on this one sorry.

Cheers,
Maxime

1 Like
5

Hi,

Yes, as the JCC python wrapper will not discover all inherited methods, a change in the underlying code which is invisible from a java API perspective, may have effects on the Python API.

The solution is as indentified above, to cast_ it to the class type which has the methods to be reached. The syntax is ClassTypeToBeCastedTo.cast_(object_to_cast). So in the case above it may become EventDetector.cast(obj) if EventDetector has that method.

The PythonEventDetector should be used when subclassing.

This is indeed a limitation, which is not in the new orekit_jpype wrapper (which has some other limitations however).

1 Like
6

Hi,

Thanks a lot that was exactly what I needed.

Indeed, I replaced apply(lambda x: event.g(x)) by apply(lambda x: EventDetector.cast_(event).g(x)). (it was an EclipseDetector)

For the propagator it worked the same with replacing propagator.getPVCoordinates by Propagator.cast_(propagator).getPVCoordinates

I will follow closely the developments of the new orekit_jpype wrapper which is very promissing !

Cheers,
Augustin