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Many types (typically collections) define their own Stream
type which goes over its elements in series, even if the collection
is not ordered, and only visits each element once. This type's prototype
is accessed via the slot ReadStream within each collection
(located on its traits object). So ``Set ReadStream''
refers to the prototype suitable for iterating over Sets.
In order to create a new iterator for a specific collection, the iterator
message is provided, which clones the prototype for that collection's
type and targets it to the receiver of the message. The protocol summary:
- iterator
- will return a ReadStream or preferably
a ReadWriteStream if one is available for the type.
- reader
- and writer get streams with only
ReadStream and WriteStream capabilities for the
type, when available.
The stream capabilities supported for each basic collection type are
usually limited by the behavior that the type supports. The capabilities
per basic type are as follows; types not mentioned inherit or specialize
the capabilities of their ancestors:
Type |
Capabilities
Collection |
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Brian Rice
2004-08-24