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authorAndy Wingo <wingo@pobox.com>2011-02-09 20:54:22 +0100
committerAndy Wingo <wingo@pobox.com>2011-02-09 20:56:04 +0100
commitc5f30c4cba204114008b8ddc8ecea5a081be69b7 (patch)
tree25280cc6b74707f3d3d353a713f762e0555293f8 /doc/ref/api-binding.texi
parent9970cf67080b48ec35680c70146500428b47bf3e (diff)
downloadguile-c5f30c4cba204114008b8ddc8ecea5a081be69b7.tar.gz
add define-once
* module/ice-9/boot-9.scm (define-once): New syntax. * doc/ref/api-binding.texi (Top Level): * NEWS: Add notes about define-once.
Diffstat (limited to 'doc/ref/api-binding.texi')
-rw-r--r--doc/ref/api-binding.texi19
1 files changed, 18 insertions, 1 deletions
diff --git a/doc/ref/api-binding.texi b/doc/ref/api-binding.texi
index 60af45680..c97ae7390 100644
--- a/doc/ref/api-binding.texi
+++ b/doc/ref/api-binding.texi
@@ -1,6 +1,6 @@
@c -*-texinfo-*-
@c This is part of the GNU Guile Reference Manual.
-@c Copyright (C) 1996, 1997, 2000, 2001, 2002, 2003, 2004, 2009, 2010
+@c Copyright (C) 1996, 1997, 2000, 2001, 2002, 2003, 2004, 2009, 2010, 2011
@c Free Software Foundation, Inc.
@c See the file guile.texi for copying conditions.
@@ -88,6 +88,23 @@ longer visible.
Attention: Scheme definitions inside local binding constructs
(@pxref{Local Bindings}) act differently (@pxref{Internal Definitions}).
+Many people end up in a development style of adding and changing
+definitions at runtime, building out their program without restarting
+it. (You can do this using @code{reload-module}, the @code{reload} REPL
+command, the @code{load} procedure, or even just pasting code into a
+REPL.) If you are one of these people, you will find that sometimes you
+there are some variables that you @emph{don't} want to redefine all the
+time. For these, use @code{define-once}.
+
+@fnindex defvar
+@deffn {Scheme Syntax} define-once name value
+Create a top level variable named @var{name} with value @var{value}, but
+only if @var{name} is not already bound in the current module.
+@end deffn
+
+Old Lispers probably know @code{define-once} under its Lisp name,
+@code{defvar}.
+
@node Local Bindings
@subsection Local Variable Bindings