XEmacs 21.2.34 "Molpe".

[chise/xemacs-chise.git.1] / info / lispref.info-8

diff --git a/info/lispref.info-8 b/info/lispref.info-8
index 445d0fc..e9ddbe6 100644 (file)
--- a/info/lispref.info-8
+++ b/info/lispref.info-8
@@ -50,6 +50,43 @@ may be included in a translation approved by the Free Software
 Foundation instead of in the original English.
 
 \1f
+File: lispref.info,  Node: Self-Evaluating Forms,  Next: Symbol Forms,  Up: Forms
+
+Self-Evaluating Forms
+---------------------
+
+   A "self-evaluating form" is any form that is not a list or symbol.
+Self-evaluating forms evaluate to themselves: the result of evaluation
+is the same object that was evaluated.  Thus, the number 25 evaluates to
+25, and the string `"foo"' evaluates to the string `"foo"'.  Likewise,
+evaluation of a vector does not cause evaluation of the elements of the
+vector--it returns the same vector with its contents unchanged.
+
+     '123               ; An object, shown without evaluation.
+          => 123
+     123                ; Evaluated as usual--result is the same.
+          => 123
+     (eval '123)        ; Evaluated "by hand"--result is the same.
+          => 123
+     (eval (eval '123)) ; Evaluating twice changes nothing.
+          => 123
+
+   It is common to write numbers, characters, strings, and even vectors
+in Lisp code, taking advantage of the fact that they self-evaluate.
+However, it is quite unusual to do this for types that lack a read
+syntax, because there's no way to write them textually.  It is possible
+to construct Lisp expressions containing these types by means of a Lisp
+program.  Here is an example:
+
+     ;; Build an expression containing a buffer object.
+     (setq buffer (list 'print (current-buffer)))
+          => (print #<buffer eval.texi>)
+     ;; Evaluate it.
+     (eval buffer)
+          -| #<buffer eval.texi>
+          => #<buffer eval.texi>
+
+\1f
 File: lispref.info,  Node: Symbol Forms,  Next: Classifying Lists,  Prev: Self-Evaluating Forms,  Up: Forms
 
 Symbol Forms