You almost never need a pointer to an interface. You should be passing interfaces as values—the underlying data can still be a pointer.
An interface is two fields:
- A pointer to some type-specific information. You can think of this as "type."
- Data pointer. If the data stored is a pointer, it’s stored directly. If the data stored is a value, then a pointer to the value is stored.
If you want interface methods to modify the underlying data, you must use a pointer.