为什么Python不能从Latin Extended-A写入字符（写入文件时会出现UnicodeEncodeError）？

Question

Obligatory intro noting that I've done some research

This seems like it should be straightforward (I am happy to close as a duplicate if a suitable target question is found), but I'm not familiar enough with character encodings and how Python handles them to suss it out myself. At risk of seeming lazy, I will note the answer very well may be in one of the links below, but I haven't yet seen it in my reading.

I've referenced some of the docs: Unicode HOWTO , codecs.py docs

I've also looked at some old highly-voted SO questions: Writing Unicode text to a text file? , Python, Unicode, and the Windows console

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Question

Here's a MCVE code example that demonstrates my problem:

with open('foo.txt', 'wt') as outfile:
    outfile.write('\u014d')

The traceback is as follows:

Traceback (most recent call last):
  File "<stdin>", line 2, in <module>
  File "C:\Users\cashamerica\AppData\Local\Programs\Python\Python3\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 '\u014d' in position 0: character maps to <undefined>

I'm confused because the code point U+014D is 'ō', an assigned code point, LATIN SMALL LETTER O WITH MACRON ( official Unicode source )

I can even print the the character to the Windows console (but it renders as a normal 'o'):

>>> print('\u014d')
o

Answer 1

You are using cp1252 as the default encoding, which does not include ō .

Write (and read) your file with explicit encoding:

with open('foo.txt', 'wt', encoding='utf8') as outfile:
    outfile.write('\u014d')