[elpa] externals/denote 6000313eec 118/355: Enforce sluggification of keywords; document it

[ELPA Syncer]

branch: externals/denote
commit 6000313eeccc31e03daebac8c0056d8909da4a7b
Author: Protesilaos Stavrou <info@protesilaos.com>
Commit: Protesilaos Stavrou <info@protesilaos.com>

    Enforce sluggification of keywords; document it
---
 README.org | 18 ++++++++++++++++++
 denote.el  | 32 ++++++++++++++++++++------------
 2 files changed, 38 insertions(+), 12 deletions(-)

diff --git a/README.org b/README.org
index 35450ae3b5..41a7d5ffe1 100644
--- a/README.org
+++ b/README.org
@@ -153,6 +153,24 @@ does not actually depend on org.el and/or its 
accoutrements.
 Notes are stored as a flat list in the ~denote-directory~ (i.e. no
 subdirectories).  The default path is =~/Documents/notes=.
 
+** Sluggified title and keywords
+:PROPERTIES:
+:CUSTOM_ID: h:ae8b19a1-7f67-4258-96b3-370a72c43f4e
+:END:
+
+Denote has to be highly opinionated about which characters can be used
+in file names and the file's front matter in order to enforce its
+file-naming scheme.  The private variable ~denote--punctuation-regexp~
+holds the relevant value.  In simple terms:
+
++ What we count as "illegal characters" are converted into hyphens.
+
++ Input for a file title is hyphenated and downcased.  The original
+  value is preserved only in the note's contents 
([[#h:13218826-56a5-482a-9b91-5b6de4f14261][Front matter]]).
+
++ Keywords should not have spaces or other delimiters.  If they do, they
+  are converted into hyphens.  Keywords are always downcased.
+
 * Points of entry
 :PROPERTIES:
 :CUSTOM_ID: h:17896c8c-d97a-4faa-abf6-31df99746ca6
diff --git a/denote.el b/denote.el
index d24759233d..19e578811a 100644
--- a/denote.el
+++ b/denote.el
@@ -174,7 +174,8 @@ is suspended: we use whatever the user wants."
   "Regular expression to match `denote-keywords'.")
 
 (defconst denote--punctuation-regexp "[][{}!@#$%^&*()_=+'\"?,.\|;:~`‘’“”]*"
-  "Regular expression of punctionation that should be removed.")
+  "Regular expression of punctionation that should be removed.
+We consider those characters illigal for our purposes.")
 
 (defvar denote-last-path nil "Store last path.")
 (defvar denote-last-title nil "Store last title.")
@@ -216,9 +217,15 @@ trailing hyphen."
     (replace-regexp-in-string "--+\\|\s+" "-" str))))
 
 (defun denote--sluggify (str)
-  "Make STR an appropriate file name slug."
+  "Make STR an appropriate slug for file names and related."
   (downcase (denote--slug-hyphenate (denote--slug-no-punct str))))
 
+(defun denote--sluggify-keywords (keywords)
+  "Sluggify KEYWORDS."
+  (if (listp keywords)
+      (mapcar #'denote--sluggify keywords)
+    (denote--sluggify keywords)))
+
 (defun denote--file-empty-p (file)
   "Return non-nil if FILE is empty."
   (zerop (or (file-attribute-size (file-attributes file)) 0)))
@@ -358,15 +365,16 @@ keyword is just downcased.
 With optional TYPE, format the keywords accordingly (this might
 be `toml' or, in the future, some other spec that needss special
 treatment)."
-  (cond
-   ((and (> (length keywords) 1) (not (stringp keywords)))
-    (pcase type
-      ('toml (format "[%s]" (denote--map-quote-downcase keywords)))
-      (_ (mapconcat #'downcase keywords "  "))))
-   (t
-    (pcase type
-      ('toml (format "[%S]" (downcase keywords)))
-      (_ (downcase keywords))))))
+  (let ((kw (denote--sluggify-keywords keywords)))
+    (cond
+     ((and (> (length kw) 1) (not (stringp kw)))
+      (pcase type
+        ('toml (format "[%s]" (denote--map-quote-downcase kw)))
+        (_ (mapconcat #'downcase kw "  "))))
+     (t
+      (pcase type
+        ('toml (format "[%S]" (downcase kw)))
+        (_ (downcase kw)))))))
 
 (defvar denote-tml-front-matter
   "+++
@@ -435,7 +443,7 @@ Format current time, else use optional ID."
         (denote--format-file
          (file-name-as-directory denote-directory)
          (format-time-string denote--id)
-         keywords
+         (denote--sluggify-keywords keywords)
          (denote--sluggify title)
          (denote--file-extension))))