Perspectives.Docu.Instances

A Perspectives 'program' consists of a model and some screens. Using these, the end user creates, consults, changes and deletes any number of instances of contexts and roles.

• PerspectContext
• PerspectRol
• like types, instances are identified.

A lot of the functionality of a Perspectives program boils down to traversing the rich structures of Context- and Role instances. The modeller can write down queries to traverse paths through the graph. The programmer of the core needs to traverse the same structures. He can use a number of functions to create queries in code:

• ObjectGetters are functions that asynchronously retrieve instance representations from the database and traverse from one to another.
• Combinators are higher order functions to combine basic ObjectGetters.
• The ArrayTransformer provides an abstraction to deal with sequences of values (a role can have multiple instances in a context: just think of the Guest role at a Party).