Tasks used to be eligible as a target for setVariable/getVariable and are still documented as such (https://community.bistudio.com/wiki/getVariable).
I used this in some mission designs but they are now throwing an error when trying to call getVariable. setVariable seems to be fine.
[Edit]
Per Killzone Kid's note, getVariable against a task apparently doesn't support an array (so key,default) argument. I've updated the steps to reproduce.
testTask = player createSimpletask ["Test Task"];
testTask setVariable ["Test",1];
diag_log format["%1: %2",time,(testTask getVariable "Test")];
Output is as follows:
"7.904: <null>"
This was the original "steps to reproduce" that worked "way back" (sometime in 2014) and now throws an error. Since the wiki says getVariable against a Task object can't take an array, I've changed the report but wanted to leave this in case it is helpful.
testTask = player createSimpletask ["Test Task"];
testTask setVariable ["TestValue",1];
testTask getVariable ["TestValue",0];
Throws at getVariable
Error Generic error in expression
Ok, that's true the wiki doesn't say that getVariable against a task supports a default value, though it did work that way before.
But even using only the syntax that the wiki has, it's still broken:
testTask = player createSimpletask ["Test Task"];
testTask setVariable ["Test",1];
diag_log format["%1: %2",time,(testTask getVariable "Test")];
Output is as follows:
"7.904: <null>"
I'll update the Steps to Reproduce to use syntax the wiki says should work
"though it did work that way before."
It didn't because it couldn't. Both Arma2 OA and Arma 3 have the following syntax for get/setvariable with task:
"b:TASK setvariable ARRAY"
"b:TASK getvariable STRING"
As you can see, it never had TASK getvariable ARRAY
Also, I just tested set/getvar in A2OA and it doesn't work there either. Basically this functionality is broken for a long time.
I was actively using it in an Arma 3 mission where it was working. That was in 2014 at some point, not sure exactly when because I've been away from A3 for awhile.
I'm pretty sure I even remember reading a note at some point about getVar/setVar being added for tasks, though I can't remember where.
I'm pretty sure you are confusing this with something else. Open Arma 2 OA and try it. Same syntax, same broken functionality. It has been like this for ages.
I believe you that it doesn't work in A2, but I only built the mission in A3 - after one of the game mode updates. The one where the AI could request transport after the helicopters DLC.
I was flying the mission with no errors and with everything working in the scripts, otherwise I wouldn't have come to report it.
When I'm back at a computer with some time I'll see if I can find the note that you can setVar/getVar on tasks, but ultimately its broken now/still and should be fixed.