Hi!
I copied the state stacking mechanics form
unrealscript. To this day, I have never needed it. When I thought I needed it, I ended up finding a better solution without stacking or even without state.
I consider gotoState is the general, usual case. Using the state stack is much, much less frequent; an "edge case", if you will. If you use a stack, it is doubtful that you will need more than 1 level.
The use case is: you have a "general state", and a state which acts as a "complement". The complement acts like a "sub state", modifying some methods of the base state.
You can find examples of most of the methods on my libraries in the /spec/ folder. These are tests that make sure that each method works as expected, but they also work as documentation. There's a test for state stacking:
https://github.com/kikito/stateful.lua/ ... ec.lua#L93
Admittedly, the state names are not great - because thinking about ideal places where state stacking makes sense is difficult for me. After all, it's a feature I never use myself. But the guys who made unrealscript are more intelligent than me, so they probably had good reasons to add it.
Sorry if my answer is a bit lackluster; it's a feature that I never use.
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