entity set implementation for iMesh and iGeom

[Ottmar Klaas]

Hi,

while looking at implementing entity sets, we ran into a few  
questions, and I was wondering if someone could help us sort this out.  
According to the documentation of iMesh/iGeom entity sets can be  
ordered or unordered. Based on what we could find in the  
documentation, the only differentiator between the two sets is that  
"Unordered entity sets can contain a given entity or set only once",  
opening up a variety of possible implementations for ordered sets.  
However, the naming of parameters (e.g. int isList) to differentiate  
between ordered and unordered sets seems to imply that ordered sets  
are to be implemented based on a list data structure. We were  
wondering if you can give us more information regarding the  
requirements for the entity set implementation. Is your intention to  
prescribe the implementation (classical list data structure for  
ordered sets, and a set data structure for unordered sets)? If not,  
could you define the requirements for the entity set implementations,  
e.g. how fast is random access supposed to be (e.g. O(n) or faster),  
are ordered sets order preserving in the sense that the order in which  
I add entities to an ordered set is the order in which the iterator  
will return the entities, etc.?

Thanks

Ottmar