Next: , Previous: , Up: Base classes   [Index]

1.108 MappedCollection

Defined in namespace Smalltalk
Superclass: Collection
Category: Collections-Keyed

I represent collections of objects that are indirectly indexed by names. There are really two collections involved: domain and a map. The map maps between external names and indices into domain, which contains the real association. In order to work properly, the domain must be an instance of a subclass of SequenceableCollection, and the map must be an instance of Dictionary, or of a subclass of SequenceableCollection.

As an example of using me, consider implenting a Dictionary whose elements are indexed. The domain would be a SequenceableCollection with n elements, the map a Dictionary associating each key to an index in the domain. To access by key, to perform enumeration, etc. you would ask an instance of me; to access by index, you would access the domain directly.

Another idea could be to implement row access or column access to a matrix implemented as a single n*m Array: the Array would be the domain, while the map would be an Interval.