bug#16328: 24.3.50; [PATCH] Enable narrowing to defun with function header comments also visible

[Josh <josh@foxtail.org>]

Unpolished but related: http://paste.lisp.org/display/136136


On Fri, Jan 3, 2014 at 8:38 AM, Drew Adams <drew.adams@oracle.com> wrote:
>> For languages where the programmer must resort to function header
>> comments to describe a function, I've always found it frustrating
>> that `narrow-to-defun' cuts out this often-critical information.
>>
>> This patch provides a new function `narrow-to-defun-including-
>> comments' to keep these comments visible when narrowing.
>>
>> As there may be multiple per-line comments instead of a single block
>> comment, I'm skipping back past ALL preceding comments. That seemed
>> reasonable instead of trying to guess how the author has structured
>> their comments. Stopping at an empty line would *probably* be okay,
>> but in the end I figured that potentially showing too much seemed
>> better than showing too little.
>>
>> (I've included a check for page breaks within the comments, however,
>> as I was confident about excluding anything before one of those.)
>>
>> I didn't think it was wise to encourage users to modify the
>> behaviour of `narrow-to-defun' itself (I certainly have programmatic
>> uses for that), so instead I've indicated the way to remap the
>> interactive bindings for users who wish to use this as standard.
>
> Hi Phil.  I wonder whether we couldn't just modify `narrow-to-defun',
> changing to (interactive "P") and using the unused argument as prefix
> arg to get this behavior?
>
> Perhaps someone knows more about the history of that argument.
> Grepping the Emacs sources, at least, I see no programmatic uses of
> `narrow-to-defun' that pass an argument.  And anyway, the argument
> is ignored.
>
> But presumably we would have kept the unused argument to allow
> `narrow-to-defun' to be used as a functional argument in a context
> where it might receive an argument?  If there were such uses then
> perhaps passing the prefix arg could prove problematic.  Dunno.
>
> Anyway, seems reasonable to try, or at least to investigate.
> `C-u C-x n d' would then already be one key binding for this.
>
> [BTW, I didn't check your code, but if it doesn't already, it could
> perhaps use code similar to that of `reposition-window', to determine
> the starting point for the narrowing.  That command (`C-M-l') is
> somewhat similar.]
>
>
>