[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
master 254f4766e6: functions.texi: Fix bug#58602
From: |
Stefan Monnier |
Subject: |
master 254f4766e6: functions.texi: Fix bug#58602 |
Date: |
Tue, 18 Oct 2022 16:06:53 -0400 (EDT) |
branch: master
commit 254f4766e6ef5370f75530752db5640895b9066a
Author: Stefan Monnier <monnier@iro.umontreal.ca>
Commit: Stefan Monnier <monnier@iro.umontreal.ca>
functions.texi: Fix bug#58602
* doc/lispref/functions.texi (Function Documentation): Document
`:documentation` and `function-documentation`.
---
doc/lispref/functions.texi | 38 ++++++++++++++++++++++++++++++++++++++
1 file changed, 38 insertions(+)
diff --git a/doc/lispref/functions.texi b/doc/lispref/functions.texi
index 8b858e0aa0..e110283252 100644
--- a/doc/lispref/functions.texi
+++ b/doc/lispref/functions.texi
@@ -533,6 +533,44 @@ Instead, use the @code{advertised-calling-convention}
declaration
compiler emit a warning message when it compiles Lisp programs which
use the deprecated calling convention.
+@cindex computed documentation string
+@kindex{:documentation}
+Documentation strings are usually static, but occasionally it can be
+necessary to generate them dynamically. In some cases you can do so
+by writing a macro which generates at compile time the code of the
+function, including the desired documentation string. But you can
+also generate the docstring dynamically by writing
+@code{(:documentation @var{form})} instead of the documentation
+string. This will evaluate @var{form} at run-time when the function
+is defined and use it as the documentation string@footnote{This only
+works in code using @code{lexical-binding}.}. You can also compute
+the documentation string on the fly when it is requested, by setting
+the @code{function-documentation} property of the function's symbol to
+a Lisp form that evaluates to a string.
+
+For example:
+@example
+@group
+(defun adder (x)
+ (lambda (y)
+ (:documentation (format "Add %S to the argument Y." x))
+ (+ x y)))
+(defalias 'adder5 (adder 5))
+(documentation 'adder5)
+ @result{} "Add 5 to the argument Y."
+@end group
+
+@group
+(put 'adder5 'function-documentation
+ '(concat (documentation (symbol-function 'adder5) 'raw)
+ " Consulted at " (format-time-string "%H:%M:%S")))
+(documentation 'adder5)
+ @result{} "Add 5 to the argument Y. Consulted at 15:52:13"
+(documentation 'adder5)
+ @result{} "Add 5 to the argument Y. Consulted at 15:52:18"
+@end group
+@end example
+
@node Function Names
@section Naming a Function
@cindex function definition
[Prev in Thread] |
Current Thread |
[Next in Thread] |
- master 254f4766e6: functions.texi: Fix bug#58602,
Stefan Monnier <=