Changing the defaults for empty tag shorthand in XML

collects/tests/xml/test.rkt

@@ -60,6 +60,7 @@
 (define xml-tests
   (test-suite
    "XML"
+   #:before (λ () (empty-tag-shorthand 'always))
    
    (test-suite
     "Legacy tests"   

collects/web-server/scribblings/faq.scrbl

@@ -76,7 +76,7 @@ easily built into an application via URLs.
 @section{My browser displays my page strangely: my CSS is ignored, sections are missing, etc.}
 
 @(require (for-label xml
-                     web-server/http/response-structs))
+                     web-server/http))
 
 @(define xexpr @tech[#:doc '(lib "xml/xml.scrbl")]{X-expression})
 
@@ -84,26 +84,45 @@ Most @web-server developers use @|xexpr|s for representing the
 HTML of their page. However, @|xexpr|s only represent XML and HTML is not exactly
 XML. This is a common source of problems.
 
-For example, XML allows the "empty tag shorthand", e.g. @litchar{<img src='...' />},
+For example, XML allows the "empty tag shorthand", e.g. @litchar{<img
-on every tag, while HTML occasionally requires an end tag, e.g. @link["http://www.w3.org/TR/html401/interact/forms.html#h-17.7"]{TEXTAREA}.
+src='...' />}, on every tag, while HTML occasionally requires an end
-Similarly, XML allows an end tag, e.g. @litchar{<img src='...'></img>}, on every tag, while
+tag,
-HTML occasionally forbides an end tag, e.g. @link["http://www.w3.org/TR/html401/struct/objects.html#h-13.2"]{IMG}.
+e.g. @link["http://www.w3.org/TR/html401/interact/forms.html#h-17.7"]{TEXTAREA}.
-(Of course, browsers do not necessarily implement their HTML parsing as specified and may be more or less lenient towards
+Similarly, XML allows an end tag, e.g. @litchar{<img
-XML-like HTML, so your test browser may not treat these forms as problematic.)
+src='...'></img>}, on every tag, while HTML occasionally forbides an
+end tag,
+e.g. @link["http://www.w3.org/TR/html401/struct/objects.html#h-13.2"]{IMG}.
+(Of course, browsers do not necessarily implement their HTML parsing
+as specified and may be more or less lenient towards XML-like HTML, so
+your test browser may not treat these forms as problematic.)
 
-Since the @web-server uses @racketmodname[xml] to format @|xexpr|s, it inherits @racketmodname[xml]'s default rendering behavior
+Since the @web-server uses @racketmodname[xml] to format @|xexpr|s, it
-in general and its use of "empty tag shorthand" in particular. @racketmodname[xml]'s is to always use this short hand. You
+inherits @racketmodname[xml]'s default rendering behavior in general
-can change it with the @racket[empty-tag-shorthand] parameter.
+and its use of "empty tag shorthand" in
+particular. @racketmodname[xml]'s default is always use the shorthand
+with the tags from @racket[html-empty-tags] and never otherwise. This
+list should contain the W3C's approved list. You can change it with
+the @racket[empty-tag-shorthand] parameter.
 
-You can also change your @xexpr so that an end tag is forced. For example, @racket['(textarea [(name "text")])] renders as
+You can also change your @xexpr so that an end tag is forced. For
-@litchar{<textarea name="text" />}, while @racket['(textarea [(name "text")] "")] renders as
+example, @racket['(textarea [(name "text")])] renders as
-@litchar{<textarea name="text"></textarea>}, because of the string content in the @|xexpr|.
+@litchar{<textarea name="text" />}, while @racket['(textarea [(name
+"text")] "")] renders as @litchar{<textarea name="text"></textarea>},
+because of the string content in the @|xexpr|. In this case, the end
+tag will always be present regardless of the value of
+@racket[empty-tag-shorthand]. It is not possible to force the other
+possibility; i.e., never include an end tag.
 
-You may think the @web-server could do a better job advertising that the contents it serves is more like XML by default. Unfortunately,
+You may think the @web-server could do a better job advertising that
-browser support for such @link["http://www.w3.org/TR/xhtml-media-types/#media-types"]{advertisement} is @link["http://www.w3.org/MarkUp/2004/xhtml-faq#ie"]{lacking}.
+the contents it serves is more like XML by default. Unfortunately,
-You can use @racket[make-xexpr-response] to easily customize your application's MIME type and response headers.
+browser support for such
+@link["http://www.w3.org/TR/xhtml-media-types/#media-types"]{advertisement}
+is @link["http://www.w3.org/MarkUp/2004/xhtml-faq#ie"]{lacking}.  You
+can use @racket[response/xexpr] to easily customize your
+application's MIME type and response headers.
 
-Finally, you may find Web browser inspectors such as the Safari Inspector, Firebug, and the Google Chrome error console to be useful
+Finally, you may find Web browser inspectors such as the Safari
+Inspector, Firebug, and the Google Chrome error console to be useful
 tools in identifying offending tags.
 
 @section{How do I use templates ``dynamically"?}

collects/xml/private/writer.rkt

@@ -9,15 +9,17 @@
  [empty-tag-shorthand (parameter/c (or/c (symbols 'always 'never) (listof symbol?)))]
  [html-empty-tags (listof symbol?)])
 
+(define html-empty-tags
+  '(param meta link isindex input img hr frame col br basefont base area))
+
 ;; (empty-tag-shorthand) : (U 'always 'never (listof Symbol))
 (define empty-tag-shorthand
-  (make-parameter 'always
+  (make-parameter 
-                  (lambda (x)
+   html-empty-tags
-                    (if (or (eq? x 'always) (eq? x 'never) (and (list? x) (andmap symbol? x)))
+   (lambda (x)
-                        x
+     (if (or (eq? x 'always) (eq? x 'never) (and (list? x) (andmap symbol? x)))
-                        (error 'empty-tag-shorthand "expected 'always, 'never, or a list of symbols: received ~e" x)))))
+         x
-
+         (error 'empty-tag-shorthand "expected 'always, 'never, or a list of symbols: received ~e" x)))))
-(define html-empty-tags '(param meta link isindex input img hr frame col br basefont base area))
 
 ;; gen-write/display-xml/content : (Nat Output-port -> Void) -> Content [Output-Port]-> Void
 (define (gen-write/display-xml/content dent)

collects/xml/xml.scrbl

@@ -335,14 +335,14 @@ for elements that have no content.
 When the parameter is set to @racket['always], the abbreviated
 notation is always used. When set of @racket['never], the abbreviated
 notation is never generated.  when set to a list of symbols is
-provided, tags with names in the list are abbreviated.  The default is
+provided, tags with names in the list are abbreviated.
-@racket['always].
 
 The abbreviated form is the preferred XML notation.  However, most
 browsers designed for HTML will only properly render XHTML if the
 document uses a mixture of the two formats. The
 @racket[html-empty-tags] constant contains the W3 consortium's
-recommended list of XHTML tags that should use the shorthand.}
+recommended list of XHTML tags that should use the shorthand. This
+list is the default value of @racket[empty-tag-shorthand].}
 
 @defthing[html-empty-tags (listof symbol?)]{