Adding/removing hero skills perfectly.

Is there a way to replicate what engineering upgrade skill does, only without the engineering upgrade?

Are there any specific JASS functions that eng. upgrade is known to call upon when replacing one skill with the other?

Reason - i want to make a real-time custom hero creation system, but don't want to make too many engineering upgrade skills.

hmm, well there is one other way. though using engineering would probably be easier.
the other way is to make all actual hero abilities to unit abilities, and then use dummy hero abilities for the "put skill point on skill" part.
im not really sure of this second way, ask anitarf i think he used this before the engineering was released.
cheers ani ;)

Well, I doubt my method can be of much assistance in this case.

If I understand correctly, what he wants is to completely replace a hero's skill, including replacing it in the learn menu. I never did that, what I achieved was that the hero had the same skill in his learn menu all the time, but it was just a dummy skill that didn't display any icon when learned. Instead, a unit ability was given to the hero when he learned the fake hero ability, and I could then freely level that ability.

This way, I achieved dynamic ability bonuses, but I was always working with the same ability, because the skill the hero could learn was always the same. The most you could do with this system is have a fake hero skill that is named something like "first skill", and whenever a hero learns that skill, his "first ability" would level up, whatever he chose his first ability to be. That way, heroes could dynamically choose their abilities, but the skill learning system wouldn't seem authentic.

The only way to do what engineering upgrade does is using engineering upgrade. You can disable the engineering upgrade ability for the player if you don't want to have its icon (it will still make effect)

Thanks :(

My only problem with it is that for every changeable skill i create i will have to make an engineering upgrade.

How bad is it memory and loadtime-wise?

Assuming i want to have around 100 interchangeable skills.

Well you could have just 1 engineering upgrade ability with 100 or so levels, then instead of having tons and tons of engineering upgrades, you just have one and alter its level to change the abilities as needed.

Some of the bugs you can get with EU are brilliant, i've managed to pull off a targetable mana shield, lasted about a second before the computer worked out i was doing something strange and crashed on me :P

An ability with 100 levels is at least as bad as 100 abilities with 1 levels, I actually think it is worse.

There are no problems with lots of object data except longer loading time, But that can get fixed using widgetizer