What's the difference between the completion styles "basic" and "emacs22"?

What's the difference between the completion styles "basic" and "emacs22"?

[Rodrigo Morales]

I'm currently getting familiar with the different completion styles,
so I'm trying to thoroughly understand the docstring of
=completion-styles-alist=.

I don't figure out the difference between the completion styles
=basic= and =emacs22=. They are two different styles, so I suppose
they might differ in some sense.

Here's a minimal working example that I've been using for finding
their differences (so far, I haven't been able to find an scenario
where they differ)

#+BEGIN_SRC elisp
(let ((completion-styles '(basic)))
  (completing-read "Prompt: " '("foobar"
                                "foobar1"
                                "foo1bar1"
                                "foo11bar11"
                                "foo111bar111")))
#+END_SRC

#+BEGIN_SRC elisp
(let ((completion-styles '(emacs22)))
  (completing-read "Prompt: " '("foobar"
                                "foobar1"
                                "foo1bar1"
                                "foo11bar11"
                                "foo111bar111")))
#+END_SRC

Whether we use =emacs22= or =basic= as our completion style, if the
point is at =foobar_=, only =foobar= and =foobar1= are shown. If the
point is at =foo_bar=, all candidates are shown.

Could anyone present a scenario where these two different
=completion-styles= result in different behavior?

Re: What's the difference between the completion styles "basic" and "emacs22"?

[Eli Zaretskii]

> From: Rodrigo Morales <moralesrodrigo1100@gmail.com>
> Date: Sat, 9 Sep 2023 03:41:34 +0000
> 
> I'm currently getting familiar with the different completion styles,
> so I'm trying to thoroughly understand the docstring of
> =completion-styles-alist=.
> 
> I don't figure out the difference between the completion styles
> =basic= and =emacs22=. They are two different styles, so I suppose
> they might differ in some sense.

Did you try looking for the answer in the Emacs user manual?  It
attempts to describe the difference in the node "Completion Styles":

  ‘emacs22’
       This completion style is similar to ‘basic’, except that it ignores
       the text in the minibuffer after point.  It is so-named because it
       corresponds to the completion behavior in Emacs 22.

Re: What's the difference between the completion styles "basic" and "emacs22"?

[Rodrigo Morales]

Thanks. After reading that part, I understand it. I should have looked
at the Emacs user manual.