The function naming convention used by Emacs.

The function naming convention used by Emacs.

[Hongyi Zhao]

As far as function names are concerned, are there some established
conventions used by Emacs? For example, I noticed that there are so
many functions in Emacs named by the suffix `-p', say,
`file-exists-p', `ht-equal-p', and so on. But I still can't figure out
the meaning of this suffix. Any tips will be appreciated.

Best, HZ
-- 
Assoc. Prof. Hongyi Zhao <hongyi.zhao@gmail.com>
Theory and Simulation of Materials
Hebei Vocational University of Technology and Engineering
No. 473, Quannan West Street, Xindu District, Xingtai, Hebei province

Re: The function naming convention used by Emacs.

[2QdxY4RzWzUUiLuE]

On 2021-09-26 at 19:05:36 +0800,
Hongyi Zhao <hongyi.zhao@gmail.com> wrote:

> As far as function names are concerned, are there some established
> conventions used by Emacs? For example, I noticed that there are so
> many functions in Emacs named by the suffix `-p', say,
> `file-exists-p', `ht-equal-p', and so on. But I still can't figure out
> the meaning of this suffix. Any tips will be appreciated.

The -p suffix is short for "predicate"; so file-exists-p is true if and
only if the argument names and existing file.  I learned of that
convention from Common Lisp; I don't know the entire history.

Re: The function naming convention used by Emacs.

[Emanuel Berg via Users list for the GNU Emacs text editor]

Hongyi Zhao wrote:

> As far as function names are concerned, are there some
> established conventions used by Emacs? For example,
> I noticed that there are so many functions in Emacs named by
> the suffix `-p', say, `file-exists-p', `ht-equal-p', and so
> on. But I still can't figure out the meaning of this suffix.
> Any tips will be appreciated.

It stands for "predicate", such a function returns t or nil.

there is also the "f" suffix for "function", e.g. `cl-incf'
and `cl-decf' ... and a couple of other conventions I can't
remember right now.

Speaking of CL, the convention for *global-variables* is not
encouraged in Elisp.

Other than that do this

(require 'checkdoc)

(setq checkdoc-permit-comma-termination-flag t)

(defun check-package-style ()
  (interactive)
  (let ((msg "Style check..."))
    (message msg)
    (checkdoc-current-buffer t) ; TAKE-NOTES
    (message "%sdone" msg) ))
(defalias 'check-style #'check-package-style)

and do byte-compile for more pointers ...

-- 
underground experts united
https://dataswamp.org/~incal

Re: The function naming convention used by Emacs.

[Emanuel Berg via Users list for the GNU Emacs text editor]

2QdxY4RzWzUUiLuE wrote:

>> As far as function names are concerned, are there some
>> established conventions used by Emacs? For example,
>> I noticed that there are so many functions in Emacs named
>> by the suffix `-p', say, `file-exists-p', `ht-equal-p', and
>> so on. But I still can't figure out the meaning of this
>> suffix. Any tips will be appreciated.
>
> The -p suffix is short for "predicate"; so file-exists-p is
> true if and only if the argument names and existing file.
> I learned of that convention from Common Lisp; I don't know
> the entire history.

Me neither :)

But it is from Predicate Logic which is an extension of
Propositional Logic ...

-- 
underground experts united
https://dataswamp.org/~incal

Re: The function naming convention used by Emacs.

[Hongyi Zhao]

On Sun, Sep 26, 2021 at 7:27 PM <2QdxY4RzWzUUiLuE@potatochowder.com> wrote:
[...]
> The -p suffix is short for "predicate"; so file-exists-p is true if and
> only if the argument names and existing file.  I learned of that
> convention from Common Lisp; I don't know the entire history.

Thank you for sharing your knowledge with me.

HZ

Re: The function naming convention used by Emacs.

[Hongyi Zhao]

On Sun, Sep 26, 2021 at 7:49 PM Emanuel Berg via Users list for the
GNU Emacs text editor <help-gnu-emacs@gnu.org> wrote:
>
> Hongyi Zhao wrote:
>
> > As far as function names are concerned, are there some
> > established conventions used by Emacs? For example,
> > I noticed that there are so many functions in Emacs named by
> > the suffix `-p', say, `file-exists-p', `ht-equal-p', and so
> > on. But I still can't figure out the meaning of this suffix.
> > Any tips will be appreciated.
>
> It stands for "predicate", such a function returns t or nil.
>
> there is also the "f" suffix for "function", e.g. `cl-incf'
> and `cl-decf' ... and a couple of other conventions I can't
> remember right now.
>
> Speaking of CL, the convention for *global-variables* is not
> encouraged in Elisp.
>
> Other than that do this
>
> (require 'checkdoc)
>
> (setq checkdoc-permit-comma-termination-flag t)
>
> (defun check-package-style ()
>   (interactive)
>   (let ((msg "Style check..."))
>     (message msg)
>     (checkdoc-current-buffer t) ; TAKE-NOTES
>     (message "%sdone" msg) ))
> (defalias 'check-style #'check-package-style)

Do you mean and suggest adding the above code snippets into the init file?

> and do byte-compile for more pointers ...

I now use the `--with-native-compilation' option to configure Emacs
for compilation. So, the thing you mentioned above should have been
done automatically by Emacs.

HZ

Re: The function naming convention used by Emacs.

[Pierpaolo Bernardi]

Il giorno 26 settembre 2021, alle ore 13:49, Emanuel Berg via Users list for the GNU Emacs text editor <help-gnu-emacs@gnu.org> ha scritto:

>there is also the "f" suffix for "function", e.g. `cl-incf'
>and `cl-decf' ... 

The "f" in these cases stands for "field".

Re: The function naming convention used by Emacs.

[Emanuel Berg via Users list for the GNU Emacs text editor]

Hongyi Zhao wrote:

>> Other than that do this
>>
>> (require 'checkdoc)
>>
>> (setq checkdoc-permit-comma-termination-flag t)
>>
>> (defun check-package-style ()
>>   (interactive)
>>   (let ((msg "Style check..."))
>>     (message msg)
>>     (checkdoc-current-buffer t) ; TAKE-NOTES
>>     (message "%sdone" msg) ))
>> (defalias 'check-style #'check-package-style)
>
> Do you mean and suggest adding the above code snippets into
> the init file?

Yes, if you will. And use it on your code.

>> and do byte-compile for more pointers ...
>
> I now use the `--with-native-compilation' option to
> configure Emacs for compilation. So, the thing you mentioned
> above should have been done automatically by Emacs.

Byte-compile your code after you've written it. Do it again
when you change it. Byte-compiling makes it faster to load and
run, that's the reason to do it. But as a positive
side-effect, the byte-compiler will also output errors and
warnings - so it is a tool to improve you code as well.

Do a Makefile and shell alias to it to run it, so you can
byte-compile fast in terms of the mere interface, but also so
that files you didn't change and have already byte-compiled
will not be byte-compiled again.

-- 
underground experts united
https://dataswamp.org/~incal

Re: The function naming convention used by Emacs.

[Emanuel Berg via Users list for the GNU Emacs text editor]

Pierpaolo Bernardi wrote:

>> there is also the "f" suffix for "function", e.g. `cl-incf'
>> and `cl-decf' ...
>
> The "f" in these cases stands for "field".

That so, OK, thanks.

-- 
underground experts united
https://dataswamp.org/~incal

RE: [External] : Re: The function naming convention used by Emacs.

[Drew Adams]

> >there is also the "f" suffix for "function", e.g. `cl-incf'
> >and `cl-decf' ...
> 
> The "f" in these cases stands for "field".

A suffix of `f' can stand for different things.
I think generally it stands loosely for "function".
The general idea is that some sort of function is
used to determine a generalized "place" that gets
updated in some way.

The most obvious and general case is `setf' whose
doc says that the first arg is a "function call
form" or it otherwise generally refers to a function.

And functions that are related to, or based on,
`setf' tend to use the `f' suffix.

Common Lisp uses lots of such "functions" (including
macros etc.) that are named with suffix `f'.

https://www.cs.cmu.edu/Groups/AI/html/cltl/clm/node80.html

There are also obvious exceptions where the `f'
isn't really a suffix.  E.g. `...aref', `...if',
`...of', `ldiff', `result-of', `svref'.

And less obvious exceptions, which are related
to `setf': `getf', `remf', `incf', `decf',
`rotatef', `shiftf'.

Re: [External] : Re: The function naming convention used by Emacs.

[Emanuel Berg via Users list for the GNU Emacs text editor]

Drew Adams wrote:

> Common Lisp uses lots of such "functions" (including macros
> etc.) that are named with suffix `f'.

Let's pretend I got it from there ...

Because in Elisp there seems to be the spelled-out "-function"
convention that seems to be the one to use ...

Often it is variables that indicate one is to set it to
a function, e.g.

(setq browse-url-browser-function #'w3m-browse-url)

-- 
underground experts united
https://dataswamp.org/~incal