Number: 112

Date: 17-Mar-84  0':17':49

Submitter: Sannella.PA

Source: MASINTER.PA

Subject: How to make new file devices

Lisp Version: 

Description: '
Date': 15 MAR 84 09':47 PST'
From': MASINTER.PA'
Subject': AR for Implementors Manual'
To':   LispSupport'
cc':   Kaplan, LispCore↑'
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Section on making new file devices, How To.'
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The FULLNAME field must satisfy the invariant that if you take a stream, get its FULLNAME, and pass that name back to an I/O function, it will implicity operate on the original STREAM.'
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Thus, for files on DSK or a file server, FULLNAME should be a unique ID that describes the exact identifier of the file. For devices which are external to the machine and which might change state over a LOGOUT or SYSOUT, it is important that FULLNAME actually be an identifier of the stream, so that the across-logout across-sysout feature can attempt to re-find the file.'
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For some devices, e.g., the STRING device, there is no good handle of that form, and (FULLNAME STREAM) should return STREAM. This is achieved by making the FULLNAME field of the stream be NIL (to avoid circularities.)'
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Edit-By: Sannella.PA

Edit-Date:  3-Apr-84 17':14':22

Attn: lisp

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System: Documentation

Subsystem: Internal System Documentation

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Priority: Hopefully

Status: Open

Problem Type: Documentation

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