On 11Apr2024 14:42, Olivier B. <perso.olivier.barthel...@gmail.com> wrote:
I am trying to use StringIO to capture stdout, in code that looks like this:
import sys
from io import StringIO
old_stdout = sys.stdout
sys.stdout = mystdout = StringIO()
print( "patate")
mystdout.seek(0)
sys.stdout = old_stdout
print(mystdout.read())
Well, it is not exactly like this, since this works properly
Aye, I just tried that. All good.
This code is actually run from C++ using the C Python API.
This worked quite well, so the code was right at some point. But now,
two things changed:
- Now using python 3.11.7 instead of 3.7.12
- Now using only the python limited C API
Maybe you should post the code then: the exact Python code and the exact
C++ code.
And it seems that now, mystdout.read() always misses the first two
characters that have been written to stdout.
My first ideas was something related to the BOM improperly truncated
at some point, but i am manipulating UTF-8, so the bom would be 3
bytes, not 2.
I didn't think UTF-8 needed a BOM. Somone will doubtless correct me.
However, does the `mystdout.read()` code _know_ you're using UTF-8? I
have the vague impression that eg some Windows systems default to UTF-16
of some flavour, possibly _with_ a BOM.
I'm suggesting that you rigorously check that the bytes->text bits know
what text encoding they're using. If you've left an encoding out
anywhere, put it in explicitly.
Hopefully someone has a clue on what would have changed in Python for
this to stop working compared to python 3.7?
None at all, alas. My experience with the Python C API is very limited.
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