Re: [Emacs-diffs] master b75fb81 1/4: Extend button.el to take callback data

[Stefan Monnier]

>       (make-text-button start (point)
>                       'face 'rcirc-url
>                       'follow-link t
>                       'burron-data url
>                       'action #'browse-url)

Odd.  I thought the benefit was for

    (define-button-type 'my-type 'action #'browse-url)

    [...]
    
       (make-text-button start (point)
                         'type 'my-type
                         'burron-data url)

where a closure is not an option.  In your above case, you could just use

    (make-text-button start (point)
                      'face 'rcirc-url
                      'follow-link t
                      'action (lambda () (browse-url url)))

>> Alternatively, action functions can also be closures.
> They can be, in lexical packages.

In this for the purpose of designing new APIs, we can take it for
granted that lexical-scoping is available.  It's easy enough to convert
an old package to use lexical-scoping.


        Stefan