Re: make project--find-in-file generic, add interactive filename to project-find-file

[Dmitry Gutov]

On 01/31/2016 05:23 PM, Stefan Monnier wrote:

> The idea of putting it before &optional is to force people to try and
> think if there'd be a good default.  Lots of packages use
> completing-read without passing a default simply because the author
> doesn't know about that feature.

IMHO, that might be a good reason to put DEFAULT right after &optional, 
but not before. We'll mention this argument several times more in the 
docstring, so it's not likely to be forgotten.

On the other hand, lots of GUI applications use the previous input as 
the default, in the absence of better choice. So we can consider making 
HIST non-optional, and use it for the default value when DEFAULT is not 
specified.

> Other functions might still use minibuffer-complete-and-exit.
> And for other functions we should just make sure that the behavior is
> still correct (even if not perfect) and that they have enough info to
> make the behavior "perfect".

I suppose we can add a new global variable, that both 
minibuffer-complete-and-exit and the non-default 
completion-read-function's will look at.