Need advice for naming practice for namespaces in Elisp.

Need advice for naming practice for namespaces in Elisp.

[Oleksandr Gavenko]

I read very small amount of elisp code and found practice to put '->' in the
name of elisp var/func:

  ./emacs-bzr/emacs-24/lisp/info-look.el:107:(defsubst info-lookup->topic-value (topic)
  ./emacs-bzr/emacs-24/lisp/info-look.el:110:(defsubst info-lookup->mode-value (topic mode)
  ./emacs-bzr/emacs-24/lisp/info-look.el:113:(defsubst info-lookup->regexp (topic mode)

Also I search for dot in names:

  ./emacs-bzr/trunk/lisp/erc/erc-backend.el:928:        (setf (erc-response.sender msg)
  ./emacs-bzr/trunk/lisp/erc/erc-backend.el:933:        (setf (erc-response.command msg)

and for colon:

  ./emacs-bzr/emacs-24/lisp/org/org-agenda.el:5666:	 (maxgap  (org-hh:mm-string-to-minutes
  ./emacs-bzr/emacs-24/lisp/org/org-agenda.el:5703:			      (org-minutes-to-hh:mm-string

Seems that official sources don't often use special marker to separate package
name and command and some times uses '->', ':' and '.'

I want to choose good marker for package to simplify reading my code and make
it more syntactically structured. I am feeling good with dot:

  blog4y-chunk.write
  blog4y-chunk.read

  blog4y-blog-selection.select
  blog4y-blog-selection.buffer-name
  blog4y-blog-selection.regex

but would be glad to hear any suggestion and coding practices... My be some
syntax agreement come from CL or other languages or have some historical
background...

-- 
Best regards!

RE: Need advice for naming practice for namespaces in Elisp.

[Drew Adams]

> I read very small amount of elisp code and found practice to 
> put '->' in the name of elisp var/func:
> 
> Also I search for dot in names:
> and for colon:
> 
> Seems that official sources don't often use special marker to 
> separate package name and command and some times uses '->',
> ':' and '.'
> 
> I want to choose good marker for package to simplify reading 
> my code and make it more syntactically structured.  I am
> feeling good with dot:
> 
> but would be glad to hear any suggestion and coding 
> practices...

I say use whatever you like.

The Elisp manual suggests using a hyphen (`-').  See (elisp) `Coding
Conventions':

,----
|* You should choose a short word to distinguish your program from
|  other Lisp programs.  The names of all global variables,
|  constants, and functions in your program should begin with that
|  chosen prefix.  Separate the prefix from the rest of the name with
|  a hyphen, `-'.  This practice helps avoid name conflicts, since
|  all global variables in Emacs Lisp share the same name space, and
|  all functions share another name space(1).
|
|  Occasionally, for a command name intended for users to use, it is
|  more convenient if some words come before the package's name
|  prefix.  And constructs that define functions, variables, etc.,
|  work better if they start with `defun' or `defvar', so put the
|  name prefix later on in the name.
|
|  This recommendation applies even to names for traditional Lisp
|  primitives that are not primitives in Emacs Lisp--such as
|  `copy-list'.  Believe it or not, there is more than one plausible
|  way to define `copy-list'.  Play it safe; append your name prefix
|  to produce a name like `foo-copy-list' or `mylib-copy-list'
|  instead.
|
|  If you write a function that you think ought to be added to Emacs
|  under a certain name, such as `twiddle-files', don't call it by
|  that name in your program.  Call it `mylib-twiddle-files' in your
|  program, and send mail to `bug-gnu-emacs@gnu.org' suggesting we add
|  it to Emacs.  If and when we do, we can change the name easily
|  enough.
|
|  If one prefix is insufficient, your package can use two or three
|  alternative common prefixes, so long as they make sense.
`----

Re: Need advice for naming practice for namespaces in Elisp.

[Stefan Monnier]

> I read very small amount of elisp code and found practice to put '->'
> in the name of elisp var/func:

I use -> sometimes, typically for access to a struct's fields.
This comes from my learning lispy languages via Scheme.

> Also I search for dot in names:

I (strongly) recommend against the use of "." in symbols.
"(erc-response.sender)" could also be interpreted as "(erc-response
. sender)" and historically Elisp has not been very good at resolving
this ambiguity in a reliable way.

> and for colon:

Colon is typically used in a Common-Lisp way, to separate the "module
name" from the specific definition.

> Seems that official sources don't often use special marker to separate
> package name and command and some times uses '->', ':' and '.'

Common usage is to use "-".


        Stefan

Re: Need advice for naming practice for namespaces in Elisp.

[Oleksandr Gavenko]

On 2013-02-06, Stefan Monnier wrote:

>> I read very small amount of elisp code and found practice to put '->'
>> in the name of elisp var/func:
>
> I use -> sometimes, typically for access to a struct's fields.
> This comes from my learning lispy languages via Scheme.
>
Thanks for interesting answer!

>> Also I search for dot in names:
>
> I (strongly) recommend against the use of "." in symbols.
> "(erc-response.sender)" could also be interpreted as "(erc-response
> . sender)" and historically Elisp has not been very good at resolving
> this ambiguity in a reliable way.
>
OK. Thanks for advice.

I start from dot as separator to mimic OOP language syntax... And found that
evaluation of:

  (defun foo.?bar () ())

by C-x C-e produce:

  foo\.bar

in message buffer. Same for 'foo?bar' name. Why '\.' or '\?' was printed?

(info "(elisp)Symbol Type") have:

     A symbol name can contain any characters whatever.  Most symbol names
  are written with letters, digits, and the punctuation characters
  `-+=*/'.  Such names require no special punctuation; the characters of
  the name suffice as long as the name does not look like a number.  (If
  it does, write a `\' at the beginning of the name to force
  interpretation as a symbol.)  The characters `_~!@$%^&:<>{}?' are less
  often used but also require no special punctuation.  Any other
  characters may be included in a symbol's name by escaping them with a
  backslash.

>> and for colon:
>
> Colon is typically used in a Common-Lisp way, to separate the "module
> name" from the specific definition.
>
>> Seems that official sources don't often use special marker to separate
>> package name and command and some times uses '->', ':' and '.'
>
> Common usage is to use "-".
>
I complete agree.

Also I forget to mention about '/' char:

  ./cedet/ede/ede-locate.el:307:  (cedet-idutils-create/update-database root))
  ./cedet/ede/ede-locate.el:347:  (cedet-cscope-create/update-database root))

And become understand that really have another question...

I write code which have distinct parts, so use prefixes:

  blog4y
  blog4y-chuck
  blog4y-serv

I want be able to recognise them from each other, so instead of:

  blog4y-init        ; blog4y
  blog4y-chunk-write ; blog4y-chunk
  blog4y-serv-show   ; blog4y-serv

use something like:

  blog4y-init        ; blog4y
  blog4y-chunk:write ; blog4y-chunk
  blog4y-serv:show   ; blog4y-serv

But this code is ugly:

  blog4y-serv:mode
  blog4y-serv:mode-map
  blog4y-serv:font-lock-keywords

and break elisp conventions... So what I really need is to make prefix visible
and distinct from rest part of name, like:

  blog4y-init        ; blog4y
  blog4y*chunk-write ; blog4y*chunk
  blog4y*serv-show   ; blog4y*serv

or use any other `-+=*/_~!@$%^&:<>{}?' allowed non-usual symbol.

Seems that any personal choice will be good...

Again thanks all for replays!

-- 
Best regards!