Re: Idempotency of add-hook wrt lambda expressions

[Stefan Monnier <monnier@iro.umontreal.ca>]

> Say a file contains an add-hook form with a lambda argument:
>   (add-hook 'foo-mode (lambda () (bar)))
> Annoyingly, the function will be added to the hook twice if the file
> is byte compiled, loaded, then reevaluated (such as with eval-buffer).

As a general rule, you should not put a lambda but a function name
(i.e. a symbol) instead, to avoid all those problems (and be able to
replace the function with a newer version of it).  But occasionally
a lambda is really exactly what you want, of course.


        Stefan