5.5 Stream classes

The exported streams class heterarchy includes the classes shown in Figure 5.1. Classes shown in bold are all instantiable.

Figure 5.1 Streams module classes.

<stream>

Open abstract class

The superclass of all stream classes and a direct subclass of <object>.

<positionable-stream>

Open abstract class

A subclass of <stream> supporting the Positionable Stream Protocol.

<buffered-stream>

Open abstract class

A subclass of <stream> supporting the Stream Extension Protocol and the Buffer Access Protocol.

Buffered streams support the buffer-size: init-keyword, which can be used to suggest the size of the stream's buffer. However, the instantiated stream might not use this value: it is taken purely as a suggested value.

<file-stream>

Open abstract instantiable class

The class of single-buffered streams over disk files. The class supports several init-keywords: locator:, direction:, if-exists:, and if-does-not-exist:.

When you instantiate this class, an indirect instance of it is created. The file being streamed over is opened immediately upon creating the stream.

<sequence-stream>

Open class

The class of streams over sequences. The class supports several init-keywords: contents:, direction:, start:, and end:.

This class can be used for streaming over all sequences, but there are also subclasses that are specialized for streaming over strings: see <string-stream>, page 102, <byte-string-stream>, page 63, and <unicode-string-stream>, page 105 for full details.

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System and I/O Reference - 31 MAR 2000