[PATCH v2 4/6] emacs: add optional predicate arg to `notmuch-show-mapc'

[Ethan Glasser-Camp]

Pieter Praet <pieter at praet.org> writes:

> * emacs/notmuch-show.el (notmuch-show-mapc):
>
>   If provided with optional argument PREDICATE, only call
>   FUNCTION if calling PREDICATE returns non-nil.
>
>   Also correct original docstring: 's/thread/buffer/'.
> ---

This patch was marked stale, but isn't.

> -(defun notmuch-show-mapc (function)
> -  "Iterate through all messages in the current thread with
> +(defun notmuch-show-mapc (function &optional predicate)
> +  "Iterate through all messages in the current buffer with
>  `notmuch-show-goto-message-next' and call FUNCTION for side
> -effects."
> +effects.
> +
> +If provided with optional argument PREDICATE, only call
> +FUNCTION if calling PREDICATE returns non-nil."
>    (save-excursion
>      (goto-char (point-min))
> -    (loop do (funcall function)
> +    (loop do (if predicate
> +		 (if (funcall predicate)
> +		     (funcall function))
> +	       (funcall function))

I don't like the way this if-structure looks, since I have to squint to
see whether the "else" clause matches the inner or the outer "if". Maybe
change the inner "if" to a "when" or an "and"?

Ethan