# IdTable<T> class

Namespace: [Grasshopper2.Collections](https://developer.rhino3d.com/api/gh2/namespace/grasshopper2.collections.md) · Assembly: [Grasshopper2](https://developer.rhino3d.com/api/gh2/assembly/grasshopper2.md)

```cs
public sealed class IdTable<T>
```

A fast hashset for Guid keys.

**Type parameters:**

- `T`

## Constructors

- [IdTable<T>](https://developer.rhino3d.com/api/gh2/type/grasshopper2.collections.idtable-1/ctor.md): Create a new, empty hash set.

## Methods

- [Add](https://developer.rhino3d.com/api/gh2/type/grasshopper2.collections.idtable-1/add.md): Add a new value to this hash set.
- [Duplicate](https://developer.rhino3d.com/api/gh2/type/grasshopper2.collections.idtable-1/duplicate.md): Create a shallow copy of this hash set. Value will not be duplicated.
- [Find](https://developer.rhino3d.com/api/gh2/type/grasshopper2.collections.idtable-1/find.md): Add a new value to this hash set.
- [Overwrite](https://developer.rhino3d.com/api/gh2/type/grasshopper2.collections.idtable-1/overwrite.md): Add a new value to this hash set, or overwrite an existing one with the same id.
- [Remove](https://developer.rhino3d.com/api/gh2/type/grasshopper2.collections.idtable-1/remove.md): Remove a value from this hash set.