Well the truth of the matter was that sensory keys were
added to the (security) kernel about the same time and this was because the
factory made them much more important.
Without segment keys that were manifestly read-only to the factory
(lest the instances gossip among themselves
about their respective clients via their shared code segment)
one of several more complex or more expensive schemes would have been required:
- The factory might make a duplicate copy of the code as it created each new instance,
- better the factory might make a read only copy of the code upon sealing the factory, (still no libraries shared between different types)
- The factory could trust selected segment keepers that some segments were read-only.
- Perhaps a scheme such as this might do.
Sensory keys are by no means a construct private to the factory.
Any program can use them just as the factory does.