tail

[Avi Gross]

Just FYI, UNIX had a bunch of utilities that could emulate a vanilla version of tail on a command line.
You can use sed, awk and quite a few others to simply show line N to the end of a file or other variations. 
Of course the way many things were done back then had less focus on efficiency than how to stepwise make changes in a pipeline so reading from the beginning to end was not an issue.



-----Original Message-----
From: Marco Sulla <Marco.Sulla.Python at gmail.com>
To: Chris Angelico <rosuav at gmail.com>
Cc: python-list at python.org
Sent: Wed, May 11, 2022 5:27 pm
Subject: Re: tail

On Wed, 11 May 2022 at 22:09, Chris Angelico <rosuav at gmail.com> wrote:
>
> Have you actually checked those three, or do you merely suppose them to be true?

I only suppose, as I said. I should do some benchmark and some other
tests, and, frankly, I don't want to. I don't want to because I'm
quite sure the implementation is fast, since it reads by chunks and
cache them. I'm not sure it's 100% free of bugs, but the concept is
very simple, since it simply mimics the *nix tail, so it should be
reliable.

>
> > I'd very much like to see a CPython implementation of that function. It
> > could be a method of a file object opened in binary mode, and *only* in
> > binary mode.
> >
> > What do you think about it?
>
> Still not necessary. You can simply have it in your own toolkit. Why
> should it be part of the core language?

Why not?

> How much benefit would it be
> to anyone else?

I suppose that every programmer, at least one time in its life, did a tail.

> All the same assumptions are still there, so it still
> isn't general

It's general. It mimics the *nix tail. I can't think of a more general
way to implement a tail.

> I don't understand why this wants to be in the standard library.

Well, the answer is really simple: I needed it and if I found it in
the stdlib, I used it instead of writing the first horrible function.
Furthermore, tail is such a useful tool that I suppose many others are
interested, based on this quick Google search:

https://www.google.com/search?q=python+tail

A question on Stackoverflow really much voted, many other
Stackoverflow questions, a package that seems to exactly do the same
thing, that is mimic *nix tail, and a blog post about how to tail in
Python. Furthermore, if you search python tail pypi, you can find a
bunch of other packages:

https://www.google.com/search?q=python+tail+pypi

It seems the subject is quite popular, and I can't imagine otherwise.
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