write function call _io_BufferedWriter_write_impl twice?

[Inada Naoki]

The second _io_BufferedWriter_write_impl call is for show warning like
"ResourceWarning: unclosed file <_io.BufferedRandom name='myfile'>"

Try `f.close()`, or `with open(...)`.

On Thu, May 30, 2019 at 12:03 PM Windson Yang <wiwindson at gmail.com> wrote:
>
> My script looks like this:
>
>     f = open('myfile', 'a+b')
>     f.write(b'abcde')
>
> And I also add a `printf` statement in the _io_BufferedWriter_write_impl
> <https://github.com/python/cpython/blob/ada319bb6d0ebcc68d3e0ef2b4279ea061877ac8/Modules/_io/bufferedio.c#L1910>
> function.
>
>     static PyObject * _io_BufferedWriter_write_impl(buffered *self,
> Py_buffer *buffer)
>     /*[clinic end generated code: output=7f8d1365759bfc6b
> input=dd87dd85fc7f8850]*/
>     {
>         printf("call write_impl\n");
>         PyObject *res = NULL;
>         Py_ssize_t written, avail, remaining;
>         Py_off_t offset;
>        ...
>
> After I compiled then run my script. I found _io_BufferedWriter_write_impl
> <https://github.com/python/cpython/blob/ada319bb6d0ebcc68d3e0ef2b4279ea061877ac8/Modules/_io/bufferedio.c#L1910>
> had
> been called twice which I expected only once. The second time it changed
> self->pos to an unexpected value too.
> --
> https://mail.python.org/mailman/listinfo/python-list



-- 
Inada Naoki  <songofacandy at gmail.com>