Fix python3 errors

[jcfr]

See https://github.com/SimpleITK/SlicerSimpleFilters/issues/17 and https://discourse.slicer.org/t/simple-filters-module-do-not-have-any-filters-in-latest-nightly-version/6787

[blowekamp]

Reviewing related exec code I found this:

 exec('self.filter = sitk.{0}()'.format(json["name"]), globals(), locals())

I am still trying to understand the change with Py3 exec and the context of execution, but I suppose this line will still work since it does not create a new variable in the local context.

[blowekamp]

Great fixes!

@jcfr You should have merge access when ready.

[jcfr]

Thanks for the review. I will follow up with changes later this evening.

The last one to fix is:

https://github.com/SimpleITK/SlicerSimpleFilters/blob/12efaabb0151c270e61bc7a3b3d08ad4c8db8095/SimpleFilters/SimpleFilters.py#L908-L909

Could it be simplified by simply using:

if v  == default:
  w.setCurrentIndex(w.count-1)

[blowekamp]

You can certainly try it as I'm not certain. Looking at the code: https://github.com/SimpleITK/SlicerSimpleFilters/blob/12efaabb0151c270e61bc7a3b3d08ad4c8db8095/SimpleFilters/SimpleFilters.py#L903

v will be something like self.filter.Ball ( e.g. for a morphological filter ) so the exec is used to get the value of that "enum".

Related I found this interesting stack overflow Q/A: https://stackoverflow.com/questions/2220699/whats-the-difference-between-eval-exec-and-compile

It sound like eval can be used if you just want the right hand side of an assignment. For example, this line in questions might be able to be changed into:

itemValue = eval(v)

This might do away with needing to muck with locals and globals.

[jamesobutler]

pinging status of this work @jcrf