UnicodeEncodeError in inferior python under windows

Question

I have recently started using emacs under Windows as my python IDE. I had some struggle getting python convinced that it was allowed to output UTF-8 to my terminal emulator (mintty does support unicode, after all) – setting PYTHONIOENCODING=UTF-8 did the trick – but my inferior python buffer still tries to force the “charmap” encoding onto python, even though emacs can deal with unicode.

>>> Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "p:/My Documents/test.py", line 33, in <module>
  File "c:\[...]\Anaconda3\lib\encodings\cp1252.py", line 19, in encode
    return codecs.charmap_encode(input,self.errors,encoding_table)[0]
UnicodeEncodeError: 'charmap' codec can't encode character '\u03b5' in position 0: character maps to <undefined>

How do I tell emacs to tell python to just get on with it and use UTF-8?

Answer 1

The solution is to just set the same environment variable to the same value as in your question. How that is done I was reminded of by an answer to a previous, similar question – which I asked myself, but had forgotten about: It's as simple as adding

(setenv "PYTHONIOENCODING" "UTF-8")

to your emacs startup file.