Re: Evaluation of hooks

[Tom Breton]

Sebastian Tennant <sebyte@smolny.plus.com> writes:

> Hi all,
> 
> I would like to add a function to my emacs-lisp-mode-hook so that whenever I
> visit emacs source files, view-mode minor mode is enabled.
> 
>   (add-hook 'emacs-lisp-mode-hook
>         (lambda ()
>           (when (>= (compare-strings
>                (buffer-file-name) 1 nil "/usr/share/emacs/" 1 nil) 17)
>             (view-mode-enable))))
> 
> With the above code in my ~/.emacs, I get the following message at startup:
> 
>   >: Wrong type argument: stringp, nil

I doubt that has anything to do with hooks.
 
> but apart from this the startup process is unaffected, and the function is
> successfully added to my emacs-lisp-mode-hook, as you can see:
> 
> ((lambda nil
>    (when
>        (>
>       (compare-strings
>        (buffer-file-name)
>        0 nil "/usr/share/emacs/" 0 nil)
>       18)
>      (view-mode-enable))))

Nope, that doesn't work either ... sometimes.

Try it in a few different buffers - especially those like *Article*
that aren't visiting a file.  The result is different depending on
what buffer you try it in.

The bug seems to be that when `buffer-file-name' does not return a
string, `compare-strings' justifiably barfs.

-- 
Tom Breton, the calm-eyed visionary
Ho ho ho, Merry Whatever!