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master d652efc: Make 'mapconcat' argument 'separator' optional
From: |
Stefan Kangas |
Subject: |
master d652efc: Make 'mapconcat' argument 'separator' optional |
Date: |
Tue, 5 Oct 2021 09:38:48 -0400 (EDT) |
branch: master
commit d652efcd087099c71cd76c4bbf2bbf04314844b4
Author: Stefan Kangas <stefan@marxist.se>
Commit: Stefan Kangas <stefan@marxist.se>
Make 'mapconcat' argument 'separator' optional
* src/fns.c (Fmapconcat): Make third 'separator' argument
optional. (Bug#50965)
* doc/lispref/functions.texi (Mapping Functions): Update
documentation for above change.
* test/src/fns-tests.el (fns-tests-mapconcat): New test.
* doc/misc/cl.texi (Obsolete Setf Customization): Don't use third
mapconcat argument in example.
* lisp/emacs-lisp/subr-x.el (string-join): Doc fix.
---
doc/lispref/functions.texi | 9 ++++-----
doc/misc/cl.texi | 2 +-
etc/NEWS | 4 ++++
lisp/emacs-lisp/subr-x.el | 4 +++-
src/fns.c | 8 ++++++--
test/src/fns-tests.el | 17 +++++++++++++++++
6 files changed, 35 insertions(+), 9 deletions(-)
diff --git a/doc/lispref/functions.texi b/doc/lispref/functions.texi
index c856557..3163300 100644
--- a/doc/lispref/functions.texi
+++ b/doc/lispref/functions.texi
@@ -961,14 +961,14 @@ side-effects only---the values it returns are ignored,
not collected
into a list. @code{mapc} always returns @var{sequence}.
@end defun
-@defun mapconcat function sequence separator
+@defun mapconcat function sequence &optional separator
@code{mapconcat} applies @var{function} to each element of
@var{sequence}; the results, which must be sequences of characters
(strings, vectors, or lists), are concatenated into a single string
return value. Between each pair of result sequences, @code{mapconcat}
inserts the characters from @var{separator}, which also must be a
-string, or a vector or list of characters. @xref{Sequences Arrays
-Vectors}.
+string, or a vector or list of characters; a @code{nil} value is
+treated as the empty string. @xref{Sequences Arrays Vectors}.
The argument @var{function} must be a function that can take one
argument and returns a sequence of characters: a string, a vector, or
@@ -986,8 +986,7 @@ string.
@group
(mapconcat (lambda (x) (format "%c" (1+ x)))
- "HAL-8000"
- "")
+ "HAL-8000")
@result{} "IBM.9111"
@end group
@end example
diff --git a/doc/misc/cl.texi b/doc/misc/cl.texi
index 1e5d40b..04e2c71 100644
--- a/doc/misc/cl.texi
+++ b/doc/misc/cl.texi
@@ -5030,7 +5030,7 @@ The above @code{incf} example could be written using
@ignore
(defmacro concatf (place &rest args)
(gv-letplace (getter setter) place
- (macroexp-let2 nil v (mapconcat 'identity args "")
+ (macroexp-let2 nil v (mapconcat 'identity args)
(funcall setter `(concat ,getter ,v)))))
@end ignore
@end defmac
diff --git a/etc/NEWS b/etc/NEWS
index 2dcd12f..e9fcfba 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -118,6 +118,10 @@ with recent versions of Firefox.
* Lisp Changes in Emacs 29.1
++++
+** Third 'mapconcat' argument 'separator' is now optional.
+An explicit nil always meant the empty string, now it can be left out.
+
---
** Themes can now be made obsolete.
Using 'make-obsolete' on a theme is now supported. This will make
diff --git a/lisp/emacs-lisp/subr-x.el b/lisp/emacs-lisp/subr-x.el
index ecd3ca8..8d6bb19 100644
--- a/lisp/emacs-lisp/subr-x.el
+++ b/lisp/emacs-lisp/subr-x.el
@@ -208,7 +208,9 @@ The variable list SPEC is the same as in `if-let'."
(string= string ""))
(defsubst string-join (strings &optional separator)
- "Join all STRINGS using SEPARATOR."
+ "Join all STRINGS using SEPARATOR.
+Optional argument SEPARATOR must be a string, a vector, or a list of
+characters; nil stands for the empty string."
(mapconcat #'identity strings separator))
(define-obsolete-function-alias 'string-reverse 'reverse "25.1")
diff --git a/src/fns.c b/src/fns.c
index a72e41a..6118285 100644
--- a/src/fns.c
+++ b/src/fns.c
@@ -2852,12 +2852,16 @@ mapcar1 (EMACS_INT leni, Lisp_Object *vals, Lisp_Object
fn, Lisp_Object seq)
return leni;
}
-DEFUN ("mapconcat", Fmapconcat, Smapconcat, 3, 3, 0,
+DEFUN ("mapconcat", Fmapconcat, Smapconcat, 2, 3, 0,
doc: /* Apply FUNCTION to each element of SEQUENCE, and concat the
results as strings.
In between each pair of results, stick in SEPARATOR. Thus, " " as
SEPARATOR results in spaces between the values returned by FUNCTION.
+
SEQUENCE may be a list, a vector, a bool-vector, or a string.
-SEPARATOR must be a string, a vector, or a list of characters.
+
+Optional argument SEPARATOR must be a string, a vector, or a list of
+characters; nil stands for the empty string.
+
FUNCTION must be a function of one argument, and must return a value
that is a sequence of characters: either a string, or a vector or
list of numbers that are valid character codepoints. */)
diff --git a/test/src/fns-tests.el b/test/src/fns-tests.el
index 5759457..2d641cc 100644
--- a/test/src/fns-tests.el
+++ b/test/src/fns-tests.el
@@ -430,6 +430,23 @@
(buffer-hash))
(sha1 "foo"))))
+(ert-deftest fns-tests-mapconcat ()
+ (should (string= (mapconcat #'identity '()) ""))
+ (should (string= (mapconcat #'identity '("a" "b")) "ab"))
+ (should (string= (mapconcat #'identity '() "_") ""))
+ (should (string= (mapconcat #'identity '("A") "_") "A"))
+ (should (string= (mapconcat #'identity '("A" "B") "_") "A_B"))
+ (should (string= (mapconcat #'identity '("A" "B" "C") "_") "A_B_C"))
+ ;; non-ASCII strings
+ (should (string= (mapconcat #'identity '("Ä" "ø" "☭" "தமிழ்") "_漢字_")
+ "Ä_漢字_ø_漢字_☭_漢字_தமிழ்"))
+ ;; vector
+ (should (string= (mapconcat #'identity ["a" "b"] "") "ab"))
+ ;; bool-vector
+ (should (string= (mapconcat #'identity [nil nil] "") ""))
+ (should-error (mapconcat #'identity [nil nil t])
+ :type 'wrong-type-argument))
+
(ert-deftest fns-tests-mapcan ()
(should-error (mapcan))
(should-error (mapcan #'identity))
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