Use System.Diagnostics.Process to implement subprocess.Popen, which could be used on posix and windows

[jameslan]

Fix #541

[slozier]

Thanks. Nice way to get things working on posix. Did you look at the ipy2 mono implementation (https://github.com/IronLanguages/ironpython2/blob/master/Src/StdLib/Lib/subprocess.py)? There might be something useful in there.

Is there any advantage to using this on windows instead of the standard implementation? If not maybe give priority to the if mswindows conditional.

[jameslan]

Is there any advantage to using this on windows instead of the standard implementation?

I was trying to keep consistency across OSes on IronPython implementation, i.e. IronPython provides identical capability on all OSes, which is limited only by the API design of dotnet.

The reason for this choice is simple for me: since with this approach, we can't make it exactly the same as CPython on POSIX, why not just make it align with dotnet on all OSes.

Basically I am not very sure how important, from the users' perspective, to keep the behavior identical to CPython.

[jameslan]

CPython.test_subprocess is still ignored, because it has many cases running ipy -c "import sys; sys.stdout.write('text')", but there's nothing output.

[slozier]

Thanks, this is great!

[slozier]

CPython.test_subprocess is still ignored, because it has many cases running ipy -c "import sys; sys.stdout.write('text')", but there's nothing output.

Interesting, I think it's not flushing before the process terminates.