I've been reading about the definition of the sandbox pattern and reading one answer given here. In the idea of a real world sandbox, it wasn't made only to prevent the children from leaving it, but also to prevent unwanted visitors from entering it.
What is the name of the pattern for this second situation? Where the software runs in a controlled space to prevent outsiders from interfering.
This "preventing outsiders from interfering" is achieved by sandboxing the outsiders, too. When everyone can't leave their sandbox, no one can enter their neighbour's sandbox. Ideally, the code that maintains the sandboxes is as lean as possible, to reduce the number of "outsiders that can interfere" as much as possible.
"Filtering" is a generic term for controlling what inputs that reach a piece of code.
A "firewall" is a membrane around a resource that filters inputs.
If you surround your sandbox with metal detectors to allow guests without metal weapons from entering the sandbox, and also erect a firewall so that the only way anyone can enter the sandbox is via the metal detectors, then you've filtered out metal weapons from the set of objects that can reach the sandbox.
