Add a handler

Add a handler

[Germán Arias]

Hi,

How add a handler at "file-name-handler-alist"?

Thanks.

Re: Add a handler

[Tassilo Horn]

Germán Arias <germanandre@gmx.es> writes:

Hi Germán,

> How add a handler at "file-name-handler-alist"?

Something like

  (add-to-list file-name-handler-alist
               (cons "\\.foobar\\'" #'my-foobar-handler))

should do the trick.

Bye,
Tassilo

Re: Add a handler

[Michael Albinus]

Germán Arias <germanandre@gmx.es> writes:

> Hi,

Hi,

> How add a handler at "file-name-handler-alist"?

First, you shall know which file names the handler is supposed to
handle. You need a regexp for this, let's say "handled\\'". This would
match all files which names have "handled" at their end (it's a stupid
example, just for illustration).

Second, you need to write a function (the "handler"), which does the
work. It must have a general argument list, which would cover all
supported operations. Something like this:

(defun my-file-name-handler  (operation &rest args)
  "Invoke my file name handler."
  (message "my-file-name-handler %s %s" operation args))

Third, you must add both to `file-name-handler-alist as cons cell:

(add-to-list 'file-name-handler-alist
             (cons "handled\\'" 'my-file-name-handler))

If a magic file name operation is called now with a file name matching
your regexp, your file name handler is called:

(file-exists-p "/path/to/this-file-name-is-handled")

would write into the *Messages* buffer

my-file-name-handler expand-file-name (/path/to/this-file-name-is-handled nil)

That's all. Now you need only to implement all supported operations, see
(info "(elisp)Magic File Names")

You could also check `file-name-handler-alist' for existing file name
handlers, and steal^W be inspired by their implementation.

> Thanks.

Best regards, Michael.

Re: Add a handler

[Germán Arias]

On 2014-04-23 00:34:50 -0600 Michael Albinus <michael.albinus@gmx.de> wrote:

> Germán Arias <germanandre@gmx.es> writes:
> 
>> Hi,
> 
> Hi,
> 
>> How add a handler at "file-name-handler-alist"?
> 
> First, you shall know which file names the handler is supposed to
> handle. You need a regexp for this, let's say "handled\\'". This would
> match all files which names have "handled" at their end (it's a stupid
> example, just for illustration).
> 
> Second, you need to write a function (the "handler"), which does the
> work. It must have a general argument list, which would cover all
> supported operations. Something like this:
> 
> (defun my-file-name-handler  (operation &rest args)
>   "Invoke my file name handler."
>   (message "my-file-name-handler %s %s" operation args))
> 
> Third, you must add both to `file-name-handler-alist as cons cell:
> 
> (add-to-list 'file-name-handler-alist
>              (cons "handled\\'" 'my-file-name-handler))
> 
> If a magic file name operation is called now with a file name matching
> your regexp, your file name handler is called:
> 
> (file-exists-p "/path/to/this-file-name-is-handled")
> 
> would write into the *Messages* buffer
> 
> my-file-name-handler expand-file-name (/path/to/this-file-name-is-handled nil)
> 
> That's all. Now you need only to implement all supported operations, see
> (info "(elisp)Magic File Names")
> 
> You could also check `file-name-handler-alist' for existing file name
> handlers, and steal^W be inspired by their implementation.
> 
>> Thanks.
> 
> Best regards, Michael.
> 

Thanks, now I can add my handler, but don't seems to work. As you suggest I will see the existing handlers to take ideas.

Regards.
Germán.