Documentation for `io.TextIOWrapper` [[1]] suggests that the buffer supplied to the constructor should be of `io.BufferedIOBase` type:
> A buffered text stream over a `BufferedIOBase` binary stream. Looking at the implementation of `io.TextIOWrapper` in both `Modules/_io/textio.c` [[2]] and `Lib/_pyio.py` [[3]], it seems like `io.TextIOWrapper` will only use the following attributes and functions on the supplied `buffer` object: ```python buffer.closed buffer.close() buffer._dealloc_warn() # ^ only from Modules/_io/textio.c, looks like failures will be ignored buffer.fileno() buffer.flush() buffer.isatty() buffer.name # ^ only when TextIOWrapper.buffer is accessed buffer.raw() # ^ only if buffer is instance of BufferedReader, BufferedWriter # or BufferedRandom, also only from Modules/_io/textio.c buffer.read() buffer.read1() # only if buffer has a read1 method buffer.readable() buffer.seek() buffer.seekable() buffer.tell() buffer.truncate() buffer.writable() buffer.write() ``` More specifically, `io.TextIOWrapper` looks like it will work fine with `buffer` objects that does not have any of the following attributes and methods that only exists in `io.BufferedIOBase`, but not in `io.RawIOBase`: ```python buffer.raw # ^ this is only called if buffer is an instance of # explicit subclasses of `io.BufferedIOBase` buffer.detatch() # this is never called buffer.read1() # this is only used if it exists buffer.readinto() # this is never called buffer.readinto1() # this is never called ``` Or stated differently, it looks like `io.TextIOWrapper` will work equally well with buffer objects that are either `io.RawIOBase` or `io.BufferedIOBase` types. So the question is, if my assessment is correct, should the documentation not be updated to clearly state that the `buffer` can be either a `io.RawIOBase` or `io.BufferedIOBase` object? (text written for python 3.7.12) [1]: https://docs.python.org/3.7/library/io.html#io.TextIOWrapper [2]: https://github.com/python/cpython/blob/v3.7.12/Modules/_io/textio.c [3]: https://github.com/python/cpython/blob/v3.7.12/Lib/_pyio.py -- https://mail.python.org/mailman/listinfo/python-list
