Re: Using org-agenda-time-grid with lists

[Marco Wahl]

Hi Steve!

> I have made two versions for calling org-agenda-time-grid, but the first does 
> not
> comply with what the last call does.  Yet the parameters are identical.
>
> (setq grid-displ '(today daily require-timed))
> (setq tm '(number-sequence 800 2000 100))
> (message "tm: %s" tm)
> (setq org-agenda-time-grid '('grid-displ 'tm
>    "......" "----------------"))
>
> (setq org-agenda-time-grid '((today daily require-timed)
>    (800 900 1000 1100 1200 1300 1400 1500 1600 1700  1800 2000)
>    "......" "----------------"))

Possibly my last answer was not so clear.

IIUC you want to use some variables (concretely grid-displ and tm)
instead of the hardcoded values in the setting of org-agenda-time-grid.

This is a Lisp question AFAICT.

    (setq org-agenda-time-grid '((today daily require-timed)
        (800 900 1000 1100 1200 1300 1400 1500 1600 1700  1800 2000)
        "......" "----------------"))

evaluates (C-x C-e) to

((today daily require-timed) (800 900 1000 1100 1200 1300 1400 1500 1600
1700 1800 2000) "......" "----------------")

and the agenda appears as expected, I guess.

Let's check the details and use some variables.

    (number-sequence 800 2000 100)

evaluates to

(800 900 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000)

LGTM.

Introduce variables grid-displ and tm

    (setq grid-displ '(today daily require-timed))
    (setq tm '(number-sequence 800 2000 100))

Ok.

Let's check some variants using those variables

    (setq org-agenda-time-grid '(grid-displ
        tm
        "......" "----------------"))

evaluates to

(grid-displ tm "......" "----------------")

which is not the wanted value i.e. the hardcoded version above.

Somehow the variables grid-displ and tm need to get evaluated before the
setting of org-agenda-time-grid.

Next try

    (setq org-agenda-time-grid (list grid-displ
        tm
        "......" "----------------"))

This evaluates to ((today daily require-timed) (number-sequence 800 2000
100) "......" "----------------") which is closer to the hardcoded
version above. But the number-sequence call did not happen.

Function eval can do that.

    (setq org-agenda-time-grid (list grid-displ
        (eval tm)
        "......" "----------------"))

This evaluates (almost) to the hardcoded version above.

Note that function eval is considered rather bad style and should be
avoided if possible.

Possibly you can use the setting

    (setq tm (number-sequence 800 2000 100))

instead of

    (setq tm '(number-sequence 800 2000 100))
    
and then just use tm instead of (eval tm) to get the list of numbers.

If you want to dig deeper you can study the backtick notation of lisp
which provides an elegant notation for variable evaluation in lists.


HTH,
-- 
Marco