bug#51176: eww switch buffer by title

[Protesilaos Stavrou]

On 2021-10-15, 20:59 +0100, Jose Antonio Ortega Ruiz <jao@gnu.org> wrote:

> On Fri, Oct 15 2021, Lars Ingebrigtsen wrote:
>
>> Jose Antonio Ortega Ruiz <jao@gnu.org> writes:
>>
>>> Since you went for the complex config, and additional option i'd find
>>> useful for the ewww rename "flag" would be a string that specifies the
>>> format to use once the title/url part has been computed.  So one can set
>>> it to, say, "eww: %s", or whatever. I know that that use case is already
>>> covered by the possibility of specifying a function, but having to
>>> duplicate the default function just to change the final format string
>>> feels a bit overkill (and i suspect changing the format is going to be a
>>> very common reason to opt for a function call).
>>
>> I think it's best to leave that sort of flexibility to the function
>> option -- there's too many ways users may want to customise this.
>
> but, 43.45% of users will simply want to change the format and get rid
> of "# eww" at the end to see more of the title! :)
>
> specifying a format string is extremely common in many packages out
> there for things like this, and is, in my opinion, much more
> user-friendly: to change that format with a function, one has to study
> eww's api for obtaining title and url, and write a non-trivial piece of
> elisp, probably (although admittedly not necessarily) outside the
> customization interface.
>
> in other words, i find the format string option as natural and common as
> the nil and t ones (which, in a way, are also redundant and could be
> removed, since it's trivial to write a function for them).
>
> but i'm probably exaggerating: people will simply copy and paste the
> relevant piece of elisp in their init files and call it a day.  so i'll
> stop the bike-shedding now :)

How about we add a sample function in the doc string?  That would give
users all the information they need to get started, no?

Like this function:

    (defun my-eww-rename-buffer ()
      (when (eq major-mode 'eww-mode)
        (when-let ((string (or (plist-get eww-data :title)
                               (plist-get eww-data :url))))
          (rename-buffer (format "*%s*" string) t))))

And we add it here:

    (defcustom eww-auto-rename-buffer nil
      "Automatically rename EWW buffers once the page is rendered.

    When nil, do not rename the buffer.  With a non-nil value
    determine the renaming scheme, as follows:

    - `title': Use the web page's title.
    - `url': Use the web page's URL.
    - a function's symbol: Run a user-defined function that returns a
      string with which to rename the buffer.  Sample of a
      user-defined function:

        (defun my-eww-rename-buffer ()
          (when (eq major-mode 'eww-mode)
            (when-let ((string (or (plist-get eww-data :title)
                                   (plist-get eww-data :url))))
              (rename-buffer (format \"*%s*\" string) t))))

    The string of `title' and `url' is always truncated to the value
    of `eww-buffer-name-length'."
      :version "29.1"
      :type '(choice
              (const :tag "Do not rename buffers (default)" nil)
              (const :tag "Rename buffer to web page title" title)
              (const :tag "Rename buffer to web page URL" url)
              (function :tag "A user-defined function to rename the buffer"))
      :group 'eww)

I can prepare a patch if you think this is worth it.

-- 
Protesilaos Stavrou
https://protesilaos.com