mapped-file-simple-stream

This simple-stream subclass is a subclass of both file-simple-stream and direct-simple-stream. Similar to file-simple-stream but opening a mapped file allows for much faster access to the file, with much less kernel overhead. Note: most operating systems do not allow the automatic extension of mapped files, so this class does not allow the extending operation either. Writes beyond the end of the file may cause an error.

A mapped file must be opened with :mapped t specified to open. The direction argument to open should be :input or :io. The file should have permissions consistent with the value specified to direction: if :input is specified, the file must be readable; if :io is specified, it must be both readable and writable.

The options when creating an instance of this class are:

• filename (required)
• direction (defaults to :input)
• if-exists
• if-does-not-exist
• external-format (defaults to :default)
• input-handle
• output-handle
• mapped
• fn-in (another name for the input-handle, for compatibility only, do not specify both)
• fn-out (another name for the output handle, for compatibility only, do not specify both)

See device-open for a description of the input-handle, output-handle, and mapped options.

See streams.htm for general information on simple-streams in Allegro CL.

Copyright (c) 1998-2008, Franz Inc. Oakland, CA., USA. All rights reserved.
Documentation for Allegro CL version 8.0. This page was not revised from the 7.0 page.
Created 2005.12.9.