# Extensions upgrade to Python3
**URL:** https://discourse.slicer.org/t/extensions-upgrade-to-python3/14074
**Category:** Development
**Tags:** extensions-manager
**Created:** [October 16, 2020, 9:23am UTC](https://discourse.slicer.org/t/extensions-upgrade-to-python3/14074 "2020-10-16T09:23:17Z")
**Posts on this page:** 7
**Page:** 1
### Author:  [@Frederic](https://discourse.slicer.org/u/Frederic)
#### Post date: [October 16, 2020, 9:23am UTC](https://discourse.slicer.org/t/extensions-upgrade-to-python3/14074/1 "2020-10-16T09:23:17Z")
Hi all,
Our extension ([GeodesicSlicer](https://github.com/FredericBr/SlicerGeodesic)) does not work in the last version of Slicer (4.11.20200903) because it needs to be ported for python3. I have to do that in a couple of days (or may I have to wait the Slicer5?).
But even if I upgraded it for Python 3, is it possible to keep a version compatible with the previous version of Slicer (and thus Python2, if yes, how to do that)?
Thanks,
Frederic
---
### Author:  [@lassoan](https://discourse.slicer.org/u/lassoan)
#### Post date: [October 16, 2020, 2:42pm UTC](https://discourse.slicer.org/t/extensions-upgrade-to-python3/14074/2 "2020-10-16T14:42:07Z")
What seems to work best for most extensions is to create a separate branch for each Slicer major.minor release:
- create a `4.10` branch from your current master (if you want to make further fixes or improvements in this version, you can do that in this branch)
- update your s4ext file for SLicer-4.10 to use this branch (in [https://github.com/Slicer/ExtensionsIndex/blob/4.10/GeodesicSlicer.s4ext](https://github.com/Slicer/ExtensionsIndex/blob/4.10/GeodesicSlicer.s4ext), change `master` to `4.10`)
- make all the necessary changes `master` branch to make your extension work in the current Slicer version
See for example how it is done for MarkupsToModels:
- [https://github.com/SlicerIGT/SlicerMarkupsToModel/branches](https://github.com/SlicerIGT/SlicerMarkupsToModel/branches)
- [https://github.com/Slicer/ExtensionsIndex/blob/4.10/MarkupsToModel.s4ext#L10](https://github.com/Slicer/ExtensionsIndex/blob/4.10/MarkupsToModel.s4ext#L10)
---
### Author:  [@jcfr](https://discourse.slicer.org/u/jcfr)
#### Post date: [October 16, 2020, 2:46pm UTC](https://discourse.slicer.org/t/extensions-upgrade-to-python3/14074/3 "2020-10-16T14:46:12Z")
Looking at the migration guide may also be helpful. See [https://www.slicer.org/wiki/Documentation/Nightly/Developers/Tutorials/MigrationGuide#Python\_2\_to\_Python\_3](https://www.slicer.org/wiki/Documentation/Nightly/Developers/Tutorials/MigrationGuide#Python_2_to_Python_3)
---
### Author:  [@Frederic](https://discourse.slicer.org/u/Frederic)
#### Post date: [October 21, 2020, 1:42pm UTC](https://discourse.slicer.org/t/extensions-upgrade-to-python3/14074/4 "2020-10-21T13:42:53Z")
Thanks @lassoan and @jcfr for your valuable comments.
The first step is done, Now I have to make the changes to work with Python 3.
Best.
---
### Author:  [@Frederic](https://discourse.slicer.org/u/Frederic)
#### Post date: [October 22, 2020, 2:10pm UTC](https://discourse.slicer.org/t/extensions-upgrade-to-python3/14074/5 "2020-10-22T14:10:16Z")
I allow myself another question, if you want I can create another post.
When I use your script @lassoan ( [**ExtractSkin.py**](https://gist.github.com/lassoan/1673b25d8e7913cbc245b4f09ed853f9#file-extractskin-py), I obtain the wrong orientation (cf. pic where the yellow nose is normally in anterior) of my model.
Do you now why?
Thanks.
---
### Author:  [@Frederic](https://discourse.slicer.org/u/Frederic)
#### Post date: [October 23, 2020, 2:24pm UTC](https://discourse.slicer.org/t/extensions-upgrade-to-python3/14074/6 "2020-10-23T14:24:27Z")
I got it. It was a [coordinate problem](https://discourse.slicer.org/t/ras-to-lps-origin-shift/7075).
For the next one with the same issue, you just have to place this code (here in python) when you create you object.stl:
`writer.SetHeader("Name of the output. SPACE=RAS")`
[GeodesicSlicer](https://github.com/FredericBr/SlicerGeodesic) is now ready for Slicer 4.11!
---
### Author:  [@lassoan](https://discourse.slicer.org/u/lassoan)
#### Post date: [October 25, 2020, 1:58am UTC](https://discourse.slicer.org/t/extensions-upgrade-to-python3/14074/7 "2020-10-25T01:58:17Z")
Thanks for the update. I’ve updated the example script to export the mesh in a simpler way, by calling:
```python
slicer.vtkSlicerSegmentationsModuleLogic.ExportSegmentsClosedSurfaceRepresentationToFiles(
"c:/tmp", segmentationNode, None, "STL")
```