[Remind-Fans] Different message every N days with OMITs

[Ed Blackman]

I'm using remind to help me train for a race.  I train every N days 
(currently every other day, but would like a generic solution for future 
training), with a different set of activities to do each time.  
Sometimes I can't train on a given day due to scheduling or injury, and 
want to pick up where I left off on the next non-omitted day.

Here's what I've been able to do on my own:

OMIT 2017-02-10
OMIT 2017-02-13

set start_date '2017-02-08'
set end_date '2017-04-15'
# index 1 is the text for omitted days, index 2 is the first activity
set training_idx nonomitted(start_date, max(today(), start_date)) + 2
set training_day iif(isomitted(today()), 1, training_idx)
set activity choose(training_day, \
"rest", \
"Activity 1", \
"Activity 2", \
"Activity 3", \
"Activity 4", \
"Activity 5", \
"")

FROM [start_date] UNTIL [end_date] MSG [activity]

This produces:
$ remind -s1 runtraining
2017/02/08 * * * * Activity 1
2017/02/09 * * * * Activity 2
2017/02/10 * * * * rest
2017/02/11 * * * * Activity 3
2017/02/12 * * * * Activity 4
2017/02/13 * * * * rest
2017/02/14 * * * * Activity 5

That's almost correct, except that it doesn't alternate days.  I've 
tried adding an OMITFUNC, but days omitted by OMITFUNC aren't picked up 
by isomitted(), so the training_idx calcuations are wrong (some 
activities get skipped).  I'd like output like this from the same 
choose() arguments:

2017/02/08 * * * * Activity 1
2017/02/09 * * * * rest         # alternate day
2017/02/10 * * * * rest         # omitted
2017/02/11 * * * * Activity 2
2017/02/12 * * * * rest         # alternate day
2017/02/13 * * * * rest         # omitted
2017/02/14 * * * * Activity 3
2017/02/15 * * * * rest         # alternate day
2017/02/16 * * * * Activity 4
2017/02/17 * * * * rest         # alternate day
2017/02/18 * * * * Activity 5

Any suggestions?  Remind 03.01.10, but willing to upgrade if a newer 
version is capable of producing the desired output.

-- 
Ed Blackman