Use keyword rather than optional arguments

src/mirror-img.lisp

@@ -21,31 +21,32 @@
 
 (in-package :mirror-img)
 
-(defvar *src-tags* '("audio" "embed" "img" "input" "script" "source" "track" "video"))
+(defparameter +src-tags+ '("audio" "embed" "img" "input" "script" "source" "track" "video"))
-(defvar *href-tags* '("link"))
+(defparameter +href-tags+ '("link"))
+(defparameter *default-tags* (append +src-tags+ +href-tags+))
 
 
 ;;; Mirror-img
 ;;; ————————————————————————————————————————
 ;; pathname pathname list → string
-(defun mirror-img (html-file base-dir &optional (tags '("img")))
+(defun mirror-img (html-file base-dir &key (tags *default-tags*))
   "Attempt to mirror all remote HREF/SRC URLs of an HTML file’s tags,
 downloading them to base-dir. The remote URLs will be replaced with the
 local version, where downloading was successful.
 Returns a string of the modified page’s HTML."
   (let* ((dom (lquery:$ (lquery:initialize html-file)))
          (url→pathname-alist
-           (mirror-linked-urls dom (append *src-tags* *href-tags*) base-dir))
+           (mirror-linked-urls dom :tags tags :base-dir base-dir))
          (url→relative-url-alist
            (mapcar (lambda (pair) (cons (car pair) (namestring (cdr pair))))
                    url→pathname-alist)))
     (substitute-urls dom
                      url→relative-url-alist
-                     (append *src-tags* *href-tags*))
+                     :tags tags)
     (aref (lquery:$ dom (serialize)) 0)))
 
 ;; lquery-dom list pathname → alist
-(defun mirror-linked-urls (dom &optional (tags '("link" "img" "script")) base-dir)
+(defun mirror-linked-urls (dom &key (tags *default-tags*) base-dir)
   "Mirror all URLs in the HREF/SRC attributes of the given tags in an LQuery
 DOM, downloading them to either the current-working directory or the base-dir.
 Returns an associative list containing pairs of remote-URLs to local pathnames.
@@ -57,13 +58,13 @@ For example:
    (mapcar (lambda (url)
              (let ((download-path
                      (ensure-directories-exist
-                      (mirrored-pathname url base-dir))))
+                      (mirrored-pathname url :base-dir base-dir))))
                (if (http-fetch url download-path)
                    (cons url download-path))))
-    (linked-urls dom tags))))
+    (linked-urls dom :tags tags))))
 
 ;; lquery-dom alist list → nil
-(defun substitute-urls (dom substitution-alist &optional (tags '("img")))
+(defun substitute-urls (dom substitution-alist &key (tags '("img")))
   "Replace SRC or HREF attributes of certain tags in an LQuery DOM, based on a
 substitution associative list. The substitution alist is made up of cons-cells
 mapping replacee URLs to substition URLs.
@@ -84,7 +85,7 @@ among the given tags."
   dom)
 
 ;; string pathname → pathname
-(defun mirrored-pathname (url &optional base-dir)
+(defun mirrored-pathname (url &key base-dir)
   "Given a URL, return the corresponding path we would download it to, were we
 to mirror it."
   (let* ((url (quri:uri url))
@@ -101,7 +102,7 @@ to mirror it."
 ;;; DOM-parsing
 ;;; ————————————————————————————————————————
 ;; lquery-dom list → list
-(defun linked-urls (dom &optional (tags '("link" "img" "script")))
+(defun linked-urls (dom &key (tags *default-tags*))
   "Return a list of all URLs in the LQuery DOM contained in the given tags’
 HREF and SRC attributes."
   (flet ((url-list-of-tag (tag)