Training cancellation.

I've been wondering about the possibility of using unit recruitment as a dummy ability, and I was wondering what specific functions I would need to use to:
Cancel a unit's traning just as it begins.
Recognise its unit-type.
Disable the recruitment process.

instead of training the unit, make it purchaseable like a mercenary camp

I don't actually want to create a unit. I just wanted to know if it's possible to cancel a unit's training. But never mind.

You can order the building to cancel, which is about the same as a person pressing ESC. Cancel only has an order id, no order string. You should find that order id per search.

Many thanks! But what do you mean by 'per search?' Should I rig up a simple trigger to print the OrderID on screen when I press cancel, or what?
Also, does pressing cancel count as a 'Unit issued order with no target' event?

Yes, it does trigger Unit issued order with no target and that way I retrieved the order id in the first place (as well as any other order id I need). But in this case I just meant the search on this site. Searching for 'order cancel' or something similar should bring you the threads that contain that order id (as I wrote it several times in the past).

After a little experimentation, I'm afraid unit-training orders simply won't be suitable as dummy abilities. Issuing an immediate cancel order is ignored by the unit- there has to be a slight wait interval after the train order, before it can be cancelled. During this interval, the unit-training UI always appears.

That happens with many triggers, that they are fired right before the respective event is applied. You only have to wait 0 seconds to get at a point where you can issue the cancel order. To do that use a timer that expires after 0 seconds. The TimerStart function has a last parameter where you can pass a function that is executed after the timer expires.

It's so beautiful! Though now I have to use globals to transfer information to the handler function... Still, a real lifesaver. If I set some globals right before the TimerStart, can I guarantee they won't be modified before it elapses?

In my experience it runs instantly so the globals should not change in that time.
BTW, what do you need such dummy abilities for ? Since Channel is usually enough.

Well, basically, I was looking for a way to set up multiple no-target dummy abilities on the same unit without having to hunt down different base abilities for each one. As far as I can tell, you can access the custom unit ID more or less directly, so there's no mixups.
Why, what's the advantage of Channel?

Channel is the universal dummy ability. You can have more than one on a unit, you can set the type of targeting, you can edit a lot about the graphics, with a slight extension you can even set the type of the spell (magical, physical, ...). It has no game effect by itself so no problems there either.

Oh, yes I see now. Most useful... you can even hide the UI... so I could use it for that gold-spawn ability... hmm. There isn't any way to set the targetting to something area-based, similar to blizzard or flamestrike, is there?

Well, that's no problem- I an dummy those up conventionally. However, I am having some difficulty getting channel to display missile art using the unit-target setting. What exactly do I need to set to ensure that missile art will display properly?