Import guile-1.8 as multiple upstream tarball component

[lilypond.git] / guile18 / examples / box / README

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+                                                              -*- outline -*-
+
+* Overview
+
+This directory includes an example program for extending Guile with a
+new (and even useful) data type.
+
+
+* Build Instructions
+
+To build the example, simply type
+
+  make box
+
+in this directory.
+
+The resulting `box' program is a Guile interpreter which has one
+additional data type called `box'.
+
+
+* The Box Data Type
+
+A box is simply an object for storing one other object in.  It can be
+used for passing parameters by reference, for example.  You simply
+store an object into a box, pass it to another procedure which can
+store a new object into it and thus return a value via the box.
+
+
+** Usage
+
+Box objects are created with `make-box', set with `box-set!' and
+examined with `box-ref'.  See the following example session for usage
+details:
+
+
+** Example Session
+
+$ ./box
+guile> (define b (make-box))
+guile> b
+#<box #f>
+guile> (box-set! b '(list of values))
+guile> b
+#<box (list of values)>
+guile> (box-ref b)
+(list of values)
+guile> (quit)
+$