Write and call function from agenda (org-mode)

(I don't know lisp, so I suspect this is really simple.)

I want to write a function to simplify my org-mode and GTD setup.

I've based my org-mode setup on the write up here: http://doc.norang.ca/org-mode.html#CustomAgendaViewSetup

I want to use the "NEXT" setup (see below) for multiple tags - I can just simply cut and paste the same code over and over, but it would be so much cleaner to write a function, so rather than having this:

            (tags-todo "-WAITING-CANCELLED/!NEXT"
                       ((org-agenda-overriding-header "Next Tasks")
                        (org-agenda-skip-function 'bh/skip-projects-and-habits-and-single-tasks)
                        (org-agenda-todo-ignore-scheduled 'future)
                        (org-agenda-todo-ignore-deadlines 'future)
                        (org-tags-match-list-sublevels t)
                        (org-agenda-sorting-strategy
                         '(todo-state-down effort-up category-keep))))

I'd prefer something like:

            (MyFunction "@work")
            (MyFunction "@computer")

Where the argument to the function changes the filtering in the above code block to something like:

            (tags-todo "-WAITING-CANCELLED+<XXX>/!NEXT"

i.e.

            (tags-todo "-WAITING-CANCELLED+@work/!NEXT"

Can someone help by pointing me in the right direction?

Solution

The following should do the trick (it also includes a variable to test for whether to use + or - before the tag, defaulting to -).

(defun zin/agenda-test (tag &optional signp)
  "Simplify agenda coding, only require TAG to create new block.

SIGNP determines whether to use `+' or `-' when adding the tag.
Defaulting to `-'."
  (let ((sign (if signp "+" "-")))
    `(tags-todo ,(format "-WAITING-CANCELLED%s%s/!NEXT" sign tag)
        ((org-agenda-overriding-header "Next Tasks")
         (org-agenda-skip-function 'bh/skip-projects-and-habits-and-single-tasks)
         (org-agenda-todo-ignore-scheduled 'future)
         (org-agenda-todo-ignore-deadlines 'future)
         (org-tags-match-list-sublevels t)
         (org-agenda-sorting-strategy
          '(todo-state-down effort-up category-keep))))))

(setq org-agenda-custom-commands `(("t" "Test"
                                (,(zin/agenda-test "@tag")
                                 ,(zin/agenda-test "@test" '+)))))

You have to make sure that org-agenda-custom-commands uses the backquote syntax (`) instead of (quote ...), otherwise the commands will not expand properly.