tail

[Chris Angelico]

On Tue, 10 May 2022 at 03:47, Marco Sulla <Marco.Sulla.Python at gmail.com> wrote:
>
> On Mon, 9 May 2022 at 07:56, Cameron Simpson <cs at cskk.id.au> wrote:
> >
> > The point here is that text is a very different thing. Because you
> > cannot seek to an absolute number of characters in an encoding with
> > variable sized characters. _If_ you did a seek to an arbitrary number
> > you can end up in the middle of some character. And there are encodings
> > where you cannot inspect the data to find a character boundary in the
> > byte stream.
>
> Ooook, now I understand what you and Barry mean. I suppose there's no
> reliable way to tail a big file opened in text mode with a decent performance.
>
> Anyway, the previous-previous function I posted worked only for files
> opened in binary mode, and I suppose it's reliable, since it searches
> only for b"\n", as readline() in binary mode do.

It's still fundamentally impossible to solve this in a general way, so
the best way to do things will always be to code for *your* specific
use-case. That means that this doesn't belong in the stdlib or core
language, but in your own toolkit.

ChrisA