`pyimport` can change `set_zero_subnormals`

[thchr]

I'm not sure if this is only an issue with the Python package I'm loading, but it's annoying that it happens:

julia> get_zero_subnormals()
false

julia> using PythonCall

julia> mp = pyimport("meep")
Python: <module 'meep' from '/home/tchr/.julia/environments/v1.11/.CondaPkg/.pixi/envs/default/lib/python3.11/site-packages/meep/__init__.py'>

julia> get_zero_subnormals()
true

I got bit by that today, since it e.g. breaks parts of plotting in Makie (MakieOrg/Makie.jl#5122). Generally, having get_zero_subnormals() == true is not very nice since it breaks lots of things that make sense (e.g. -0.0 < 0.0 is then false).

Is it possible to guard against this on the PythonCall.jl side of things?

[thchr]

Thinking this over, it cannot really be PythonCall's responsibility to guard against shenanigans like this: the meep package intentionally sets subnormals to zero. Similarly, other packages might choose to set other global state - but figuring out which local state happens to be set or not seems quite brittle and is too much to put on PythonCall's shoulders.