Browse Prior Art Database

APL File Accessing Utilities

IP.com Disclosure Number: IPCOM000050102D
Original Publication Date: 1982-Sep-01
Included in the Prior Art Database: 2005-Feb-10
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Kellerman, E: AUTHOR

Abstract

Herein is described a group of general purpose routines used for reading or writing files using APL.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 100% of the total text.

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APL File Accessing Utilities

Herein is described a group of general purpose routines used for reading or writing files using APL.

These routines dynamically create and delete variables that are shared with the APL I/O Auxiliary Processor. The user is not normally aware of the existence of these shared variables. The names given to the shared variables are formed by concatenating: an unusual combination of characters (to avoid conflict

with other variables that may exist in the work space);

an "R" or a "W" (to indicate whether the file is to be read

or written; and a file id (supplied by the user).

It is through these special naming conventions that the routines keep track of which files are currently open, and whether they are open for reading or for writing. For example, if a user tries to "write" a file identified with a specific file id, the write routine determines if a variable exists in the work space with the appropriate name (which is uniquely determined from the specified file id, and from the fact that the file is to be written). If the variable exists, it is then used to write to the indicated file. If the variable does not exist, an error message is issued informing the user that the required file is not open for writing.

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