Jeffrey Kintscher <websur...@surf2c.net> added the comment:
>>> import io >>> b = io.BytesIO() >>> b.write(b'abc') 3 >>> buf = b.getbuffer() >>> b.seek(0) 0 >>> b.write(b'?') Traceback (most recent call last): File "<stdin>", line 1, in <module> BufferError: Existing exports of data: object cannot be re-sized >>> The problem is caused by the b.getbuffer() call. It increments a reference counter in the BytesIO object that causes the b.write() call to fail because the counter is > 0. The error message is misleading. The counter is decremented when the buffer view is deleted. >>> import io >>> b = io.BytesIO() >>> b.write(b'abc') 3 >>> buf = b.getbuffer() >>> b.seek(0) 0 >>> b.write(b'?') Traceback (most recent call last): File "<stdin>", line 1, in <module> BufferError: Existing exports of data: object cannot be re-sized >>> del buf >>> b.write(b'?') 1 >>> b.getvalue() b'?bc' >>> The documentation for io.BytesIO.getbuffer() says "Note: As long as the view exists, the BytesIO object cannot be resized or closed." Either this is a bug, or the documentation needs to be updated to say the io.BytesIO object is unwritable while any buffer views exist. ---------- _______________________________________ Python tracker <rep...@bugs.python.org> <https://bugs.python.org/issue41097> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
