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Is there a ObjectIdCollection one .Combine with ObjectIdCollection Two ?

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nobody:
Want to combine two ObjectIdCollections ... only what to iterate through each objectid and add to the second collection? Suppose I could create lists but just wondering more out of curiosity than anything. 

Thanks!

gile:
Hi,

There is no built-in method for combining / concatenating two ObjectIdCollections.
For my part, I avoid using ObjectIdCollection except when the AutoCAD API requires it.
Generic collections (List <Objectid>, HashSet <ObjectId>, ...) are more powerful and more flexible.

You can create an extension method to mimic the List<T>.AddRange() method:

--- Code - C#: ---    public static class Extension    {        public static void AddRange(this ObjectIdCollection ids, ObjectIdCollection otherIds)        {            foreach (ObjectId id in otherIds) ids.Add(id);        }    }
By my side, I'd rather use Linq extension methods which return a new IEnumerable<ObjectId> so that the original collections remain unchanged.

--- Code - C#: ---    public static class Extension    {        public static IEnumerable<ObjectId> Concat(this ObjectIdCollection ids, IEnumerable<ObjectId> otherIds)        {            return ids.Cast<ObjectId>().Concat(otherIds);        }         public static IEnumerable<ObjectId> Concat(this ObjectIdCollection ids, ObjectIdCollection otherIds)        {            return ids.Concat(otherIds.Cast<ObjectId>());        }    }
Then, if needed, you can easily convert the returned IEnumerable<objectId> into a concrete collection:


--- Code - C#: ---List<ObjectId> ids3 = ids1.Concat(ids2).ToList();

--- Code - C#: ---ObjectIdCollection ids4 = new ObjectIdCollection(ids1.Concat(ids2).ToArray());

nobody:
wow...thank you :) Looks super efficient.

CADbloke:
I think the functionality you are looking for is "Union" - you want to combine the ObjectIdCollections without introducing duplicates.

https://msdn.microsoft.com/en-us/library/bb341731(v=vs.110).aspx

ObjectIdCollection doesn't have it but Linq does so you would need to write it yourself. Perhaps break out the collections into List<>, Union that and then rebuild the ObjectIdCollection

The other way is to convert the ObjectIdCollections into HashTables and then combine those.

gile:
Hi,

If you want to remove duplicates, you can use Union (as CADbloke suggested) instead of Concat in the upper Linq extension methods.


--- Code - C#: ---        public static IEnumerable<ObjectId> Union(this ObjectIdCollection ids, IEnumerable<ObjectId> otherIds) =>            ids.Cast().Union(otherIds);         public static IEnumerable<ObjectId> Union(this ObjectIdCollection ids, ObjectIdCollection otherIds) =>            ids.Union(otherIds.Cast());

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