I need to classify two different types of tasks as those that repeat, and those that do not repeat (i.e. the task self-destructs after it has successfully run, and never runs again).
Right now, the former I am just going to call "repeat"; I was going to call the latter "ad hoc," but then I realized that an ad hoc task may also be repeatable.
Theoretically, what is the best way to describe the opposite of a repeatable task?
On
In practice, I suggest X task where X is an event that unambiguously only occurs once, and so the associated task necessarily only occurs once. For example "creation task" or "initialization task" or "shutdown task".
If you're looking for a general term, you're not going to find one. A task by default repeats. It's like asking for the opposite of "runner" or the term for a dvd player that only plays once. Typically, one would use "self destructing" for that. Otherwise, you're limited to using adjectives to convey your meaning. Eg "one time task". There's just not going to be a single term that represents a contradiction of two terms. Oxymoron require at least two terms to establish the contradiction.
If you want a general term, you'll need to make up your own. Oxytaskron?
Repeat is definitely going to work, although I would probably use iterate or maybe recurrent; if it could be confused with a loop.
Ad hoc is not a good choice in my opinion. I would go for onetime or simply put a non- in front of the other word (non-iterating, non-recurrent).