Address completion in Emacs

[David Edmondson]

On Fri, Dec 12 2014, Lele Gaifax wrote:
> Hi all,
>
> Yesterday I tweaked my Emacs configuration to use "ido-completing-read"
> to select the right address in the minibuffer, and noticed what seems a
> glitch in the related code.
>
> To accomplish the goal, I implemented my own selection function
>
>   (defun esk-notmuch-address-selection-function (prompt addresses first)
>     "Use `ido-completing-read' to select one of the addresses."
>     (ido-completing-read prompt (cons first addresses)
>                          nil nil nil 'notmuch-address-history))
>
> and then assigned it to `notmuch-address-selection-function':
>
>   (setq notmuch-address-selection-function 'esk-notmuch-address-selection-function)
>
> As you can see, I had to `cons' the two arguments, because the caller of
> that function does something similar to the following (where `orig' is
> the text entered before TAB-completion):
>
>   (options (notmuch-address-options orig))
>   (num-options (length options))
>   (chosen (funcall notmuch-address-selection-function
>               (format "Address (%s matches): " num-options)
>               (cdr options) (car options)))
>
> and the standard `notmuch-address-selection-function' is defined like:
>
>   (defun notmuch-address-selection-function (prompt collection initial-input)
>     "Call (`completing-read'
>         PROMPT COLLECTION nil nil INITIAL-INPUT 'notmuch-address-history)"
>     (completing-read
>      prompt collection nil nil initial-input 'notmuch-address-history))
>
> where that `initial-input' is not what I initially thought, the text
> entered by the user, but rather the first completion candidate.
>
> Wouldn't it be more "correct" to pass the unchanged `options' list and
> the "real" `orig' text as `initial-input' to the customizable function
> instead?

Would I then have to press TAB twice to get the first result?

> I understand that it may be undesiderable to break existing
> configurations by rectifying the arguments in that way, and in such case
> could we change the `initial-input' argument name to better reflect the
> fact that it actually contains one possible candidate instead?

>From the perspective of `notmuch-address-selection-function', it _is_
the `initial-input', as that is what is presented to the user.

> Thanks in advance for any clarification,
> ciao, lele.
> -- 
> nickname: Lele Gaifax | Quando vivrò di quello che ho pensato ieri
> real: Emanuele Gaifas | comincerò ad aver paura di chi mi copia.
> lele at metapensiero.it  |                 -- Fortunato Depero, 1929.
>
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