GNU bug report logs - #41981
Reference Manual on Vtables: Missing Information on Permission "h"

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Message #8 received at 41981 <at> debbugs.gnu.org (full text, mbox):

From: dsmich <at> roadrunner.com
To: "'sebastian.miele <at> gmail.com'" <sebastian.miele <at> gmail.com>
Cc: "'41981 <at> debbugs.gnu.org'" <41981 <at> debbugs.gnu.org>
Subject: RE: bug#41981: Reference Manual on Vtables: Missing Information on
 Permission "h"
Date: Sun, 21 Jun 2020 16:29:20 +0000

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Is is documented in the docstring:

scheme@(guile-user)> ,d make-struct-layout
- Scheme Procedure: make-struct-layout fields
 Return a new structure layout object.

 FIELDS must be a string made up of pairs of characters strung
 together. The first character of each pair describes a field type,
 the second a field protection. Allowed types are 'p' for
 GC-protected Scheme data, 'u' for unprotected binary data. Allowed
 protections are 'w' for normal fields or 'h' for hidden fields.

 Hidden fields are writable, but they will not consume an
 initializer arg passed to `make-struct'. They are useful to add
 slots to a struct in a way that preserves backward-compatibility
 with existing calls to `make-struct', especially for derived
 vtables.

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