Re: defadvice question.

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

Michal wrote:
> Hallo group members.
> when doing C-u M-x cvs-checkout 
> I wanted to always have in minibuffer history ring, my cvs root, just to
> use up arrow key to get it. So I did:
> 
> (setenv "CVSROOT" "/my/cvs/root")
> 
> (defadvice cvs-checkout
>   (before cvs-checkout-cvs-root-add-to-history-ring)
>   (add-to-list 'minibuffer-history (getenv "CVSROOT")))
> 
> (ad-activate 'cvs-checkout)
> 
> 
> but it does not work. Have You an idea why?

`before' advice runs after the interactive arguments are read.  See the
"Combined Definition" node of the Elisp manual (under "Advising Functions").

You can modify the interactive form, like this:

(defadvice cvs-checkout (before minibuffer-history)
   "Add CVSROOT environment variable to `minibuffer-history'."
   (interactive (let ((minibuffer-history
		      (cons (getenv "CVSROOT") minibuffer-history)))
		 ...)))

The tricky part is the "...".  You could copy the entire interactive form from
cvs-checkout source in pcvs.el, but that defeats the whole purpose of using
advice.  You might be able to work around it like this:

(defvar cvs-checkout-interactive-form
   (interactive-form 'cvs-checkout))

(defadvice cvs-checkout (before minibuffer-history)
   "Add CVSROOT environment variable to `minibuffer-history'."
   (interactive (let ((minibuffer-history
		      (cons (getenv "CVSROOT") minibuffer-history)))
		 (call-interactively `(lambda (&rest cvs-checkout-args)
					,cvs-checkout-interactive-form
					cvs-checkout-args)))))

-- 
Kevin Rodgers
Denver, Colorado, USA