From 5ce6ee75df2e05aadaf29f8a2c1bfabd7f123cbd Mon Sep 17 00:00:00 2001
From: Neil Jerram <neil@ossau.uklinux.net>
Date: Thu, 28 Sep 2006 07:55:05 +0000
Subject: [PATCH] =?UTF-8?q?(Slot=20Options):=20Added=20example=20from=20Lu?=
 =?UTF-8?q?dovic=20Court=C3=A8s=20about=20difference=20between=20init-valu?=
 =?UTF-8?q?e,=20-form=20and=20-thunk.?=
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---
 doc/goops/ChangeLog  |  5 +++++
 doc/goops/goops.texi | 36 ++++++++++++++++++++++++++++++++++--
 2 files changed, 39 insertions(+), 2 deletions(-)

diff --git a/doc/goops/ChangeLog b/doc/goops/ChangeLog
index f9c43e60b..b0e742b71 100644
--- a/doc/goops/ChangeLog
+++ b/doc/goops/ChangeLog
@@ -1,3 +1,8 @@
+2006-09-28  Neil Jerram  <neil@ossau.uklinux.net>
+
+	* goops.texi (Slot Options): Added example from Ludovic Courtès
+	about difference between init-value, -form and -thunk.
+
 2006-04-21  Kevin Ryde  <user42@zip.com.au>
 
 	* hierarchy.pdf: New file, converted from hierarchy.eps using
diff --git a/doc/goops/goops.texi b/doc/goops/goops.texi
index 171ac2bfa..d6d8e595d 100644
--- a/doc/goops/goops.texi
+++ b/doc/goops/goops.texi
@@ -838,8 +838,40 @@ value (shared across all new instances of the class).
 when a new instance is created and should return the desired initial
 slot value.  @var{init-form} is an unevaluated expression that gets
 evaluated when a new instance is created and should return the desired
-initial slot value.  @var{init-keyword} is a keyword that can be used to
-pass an initial slot value to @code{make} when creating a new instance.
+initial slot value.  @var{init-keyword} is a keyword that can be used
+to pass an initial slot value to @code{make} when creating a new
+instance.
+
+Note that, since an @code{init-value} value is shared across all
+instances of a class, you should only use it when the initial value is
+an immutable value, like a constant.  If you want to initialize a slot
+with a fresh, independently mutable value, you should use
+@code{init-thunk} or @code{init-form} instead.  Consider the following
+example.
+
+@example
+(define-class <chbouib> ()
+  (hashtab #:init-value (make-hash-table)))
+@end example
+
+@noindent
+Here only one hash table is created and all instances of
+@code{<chbouib>} have their @code{hashtab} slot refer to it.  In order
+to have each instance of @code{<chbouib>} refer to a new hash table, you
+should instead write:
+
+@example
+(define-class <chbouib> ()
+  (hashtab #:init-thunk make-hash-table))
+@end example
+
+@noindent
+or:
+
+@example
+(define-class <chbouib> ()
+  (hashtab #:init-form (make-hash-table)))
+@end example
 
 If more than one of these options is specified for the same slot, the
 order of precedence, highest first is