Re: dynamic completion-ignored-extensions

[Kevin Rodgers <kevin.d.rodgers@gmail.com>]

Kevin Ryde wrote:
> Is there a way to have a kind of dynamic completion-ignored-extensions
> so that for instance a .c file is ignored if there's a .xs of the same
> name?  Or even a kind of programmatic ignore so Makefile is not offered
> if it seems to be in a build directory of some flavour (and therefore a
> generated file).
> 
> I tried sticking a defadvice on file-name-completion, but in emacs22 it
> doesn't seem to be reached.  I guess read-file-name is C code and
> bypasses advice, or something.  Is there another filename reader that
> could be could be easily pressed into service and customized?

Right, and read-file-name is implemented in C as well, which is why
there is the read-file-name-function variable (C-h v).  Maybe something
like this will do what you want:

(defun my-read-file-name (&rest args)
   "Tweak `completion-ignored-extensions' before calling `read-file-name'."
   (let ((read-file-name-function nil)
	(completion-ignored-extensions (your-code-here)))
     (apply 'read-file-name args)))

(setq read-file-name-function 'my-read-file-name)

-- 
Kevin Rodgers
Denver, Colorado, USA